User Manual
Model 900D Series
Scanning Electrochemical Microscope
User Manual
CH Instruments
CH Instruments Model 900D Series User Manual
© 2014 CH Instruments, Inc.
All rights reserved. No parts of this work may be reproduced in any form or by any means - graphic, electronic, or
mechanical, including photocopying, recording, taping, or information storage and retrieval systems - without the
written permission of the publisher.
Products that are referred to in this document may be either trademarks and/or registered trademarks of the
respective owners. The publisher and the author make no claim to these trademarks.
While every precaution has been taken in the preparation of this document, the publisher and the author assume no
responsibility for errors or omissions, or for damages resulting from the use of information contained in this
document or from the use of programs and source code that may accompany it. In no event shall the publisher and
the author be liable for any loss of profit or any other commercial damage caused or alleged to have been caused
directly or indirectly by this document.
Printed: August 2014 in Austin, Texas.
Contents
i
Table of Contents
Chapter 1 General Information
1
1.1 Introduction
................................................................................................................................... 2
1.2 Electrochemical
...................................................................................................................................
Techniques
4
1.3 Software
...................................................................................................................................
Features
6
1.4 System...................................................................................................................................
Requirements
9
1.5 Hardware
...................................................................................................................................
Specifications
10
Chapter 2 Getting Started
11
2.1 Installation
................................................................................................................................... 12
2.1.1
2.1.2
2.1.3
2.1.4
Parts List
.......................................................................................................................................................... 13
Softw are
.......................................................................................................................................................... 14
Hardw are
.......................................................................................................................................................... 16
Nanopositioner,
..........................................................................................................................................................
Stepper Motors, and Piezo
19
2.2 USB Driver
...................................................................................................................................
Installation
22
2.3 Testing
................................................................................................................................... 25
2.4 Some...................................................................................................................................
Useful Tips
27
Chapter 3 File Menu
29
3.1 Open...................................................................................................................................
command
30
3.2 Save ...................................................................................................................................
As command
32
3.3 Delete
...................................................................................................................................
command
34
3.4 Retrieve
...................................................................................................................................
command
35
3.5 Update
...................................................................................................................................
Instrument Program command
36
3.6 List Data
...................................................................................................................................
File command
37
3.7 Convert
...................................................................................................................................
to Text command
38
3.8 Text File
...................................................................................................................................
Format command
39
3.9 Import
...................................................................................................................................
Text File command
42
3.10 Print ...................................................................................................................................
command
43
3.11 Print ...................................................................................................................................
Multiple Files command
44
3.12 Print ...................................................................................................................................
Setup command
45
3.13 Exit command
................................................................................................................................... 47
Chapter 4 Setup Menu
49
4.1 Technique
...................................................................................................................................
command
50
4.2 Parameters
...................................................................................................................................
command
52
4.2.1
4.2.2
4.2.3
4.2.4
4.2.5
© 2014 CH Instruments, Inc.
Cyclic Voltam
..........................................................................................................................................................
m etry Param eters dialog box
53
Linear ..........................................................................................................................................................
Sw eep Voltam m etry Param eters dialog box
55
Staircase
..........................................................................................................................................................
Voltam m etry Param eters dialog box
57
Tafel Plot
..........................................................................................................................................................
Param eters dialog box
58
Chronoam
..........................................................................................................................................................
perom etry Param eters dialog box
59
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CH Instruments Model 900D Series
4.2.6
4.2.7
4.2.8
4.2.9
4.2.10
4.2.11
4.2.12
4.2.13
4.2.14
4.2.15
4.2.16
4.2.17
4.2.18
4.2.19
4.2.20
4.2.21
4.2.22
4.2.23
4.2.24
4.2.25
4.2.26
4.2.27
4.2.28
4.2.29
4.2.30
4.2.31
4.2.32
4.2.33
4.2.34
4.2.35
4.2.36
..........................................................................................................................................................
61
Chronocoulom
etry Param eters dialog box
Differential
..........................................................................................................................................................
Pulse Voltam m etry Param eters dialog box
63
Norm al..........................................................................................................................................................
Pulse Voltam m etry Param eters dialog box
64
Differential
..........................................................................................................................................................
Norm al Pulse Voltam m etry dialog box
65
Square
..........................................................................................................................................................
Wave Voltam m etry Param eters dialog box
66
AC Voltam
..........................................................................................................................................................
m etry Param eters dialog box
67
2nd Harm
..........................................................................................................................................................
onic AC Voltam m etry Param eters dialog box
68
FT AC..........................................................................................................................................................
Voltam m etry Param eters dialog box
69
Am perom
..........................................................................................................................................................
etric i-t Curve dialog box
70
Differential
..........................................................................................................................................................
Pulse Am perom etry Param eters dialog box
71
Double
..........................................................................................................................................................
Differential Pulse Am perom etry dialog box
72
Triple..........................................................................................................................................................
Pulse Am perom etry Param eters dialog box
74
Integrated
..........................................................................................................................................................
Pulsed Am perom etric Detection Param eters dialog box
76
Bulk Electrolysis
..........................................................................................................................................................
w ith Coulom etry Param eters dialog box
78
Hydrodynam
..........................................................................................................................................................
ic Modulation Voltam m etry Param eters dialog box
79
Sw eep
..........................................................................................................................................................
Step Function Param eters dialog box
80
Multi-Potential
..........................................................................................................................................................
Steps Param eters dialog box
81
A.C. Im
..........................................................................................................................................................
pedance Param eters dialog box
82
Im pedance
..........................................................................................................................................................
- Tim e Param eters dialog box
84
Im pedance
..........................................................................................................................................................
- Potential Param eters dialog box
85
Chronopotentiom
..........................................................................................................................................................
etry Param eters dialog box
86
Chronopotentiom
..........................................................................................................................................................
etry w ith Current Ram p Param eters dialog box
88
Multi-Current
..........................................................................................................................................................
Steps Param eters dialog box
89
Potentiom
..........................................................................................................................................................
etric Stripping Analysis Param eters dialog box
90
Param..........................................................................................................................................................
eters for Open Circuit Potential vs Tim e dialog box
91
Param..........................................................................................................................................................
eters for Electrochem ical Noise Measurem ent dialog box
92
Surface
..........................................................................................................................................................
Patterned Conditioning Param eters dialog box
93
Probe..........................................................................................................................................................
Scan Curve Param eters dialog box
95
Probe..........................................................................................................................................................
Approach Curve Param eters dialog box
98
Surface
..........................................................................................................................................................
Interrogation SECM Param eters dialog box
100
Scanning
..........................................................................................................................................................
Electrochem ical Microscope Param eters dialog box
102
4.3 System
...................................................................................................................................
command
105
4.4 Hardware
...................................................................................................................................
Test command
108
Chapter 5 Control Menu
111
5.1 Run ...................................................................................................................................
Experiment command
112
5.2 Pause
...................................................................................................................................
/ Resume command
113
5.3 Stop...................................................................................................................................
Run command
114
5.4 Reverse
...................................................................................................................................
Scan command
115
5.5 Zero...................................................................................................................................
Current command
116
5.6 Zero...................................................................................................................................
Time command
117
5.7 Run ...................................................................................................................................
Status command
118
5.8 Repetitive
...................................................................................................................................
Runs command
121
5.9 Multiplexer
...................................................................................................................................
command
123
5.10 Macro
...................................................................................................................................
Command command
125
5.11 Open
...................................................................................................................................
Circuit Potential command
132
5.12 iR Compensation
...................................................................................................................................
command
133
5.13 Filter
...................................................................................................................................
Setting command
135
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iii
137
5.14 Cell ...................................................................................................................................
command
5.15 Step...................................................................................................................................
Functions command
140
5.16 Preconditioning
...................................................................................................................................
command
142
5.17 Rotating
...................................................................................................................................
Disk Electrode command
144
5.18 Other
...................................................................................................................................
command
145
5.19 Stripping
...................................................................................................................................
Mode command
146
5.20 SECM
...................................................................................................................................
Probe command
148
Chapter 6 Graphics Menu
151
6.1 Present
...................................................................................................................................
Data Plot command
152
6.2 Overlay
...................................................................................................................................
Plots command
156
6.3 Add ...................................................................................................................................
Data to Overlay command
157
6.4 Replot
...................................................................................................................................
Overlay command
158
6.5 Manage
...................................................................................................................................
Overlay command
159
6.6 Parallel
...................................................................................................................................
Plots command
160
6.7 Add ...................................................................................................................................
Data to Parallel command
161
6.8 Replot
...................................................................................................................................
Parallel command
162
6.9 Manage
...................................................................................................................................
Parallel command
163
6.10 Zoom
...................................................................................................................................
In command
164
6.11 Manual
...................................................................................................................................
Results command
165
6.12 Peak...................................................................................................................................
Definition command
166
6.13 X-Y Plot
...................................................................................................................................
command
167
6.14 Peak...................................................................................................................................
Parameter Plot command
169
6.15 Semilog
...................................................................................................................................
Plot command
171
6.16 Special
...................................................................................................................................
Plot command
172
6.17 Graph
...................................................................................................................................
Options command
173
6.18 Color
...................................................................................................................................
and Legend command
176
6.19 Font...................................................................................................................................
command
178
6.20 Copy...................................................................................................................................
to clipboard command
179
Chapter 7 DataProc Menu
181
7.1 Smoothing
...................................................................................................................................
command
182
7.2 Derivatives
...................................................................................................................................
command
184
7.3 Integration
...................................................................................................................................
command
185
7.4 Semiinteg
...................................................................................................................................
and Semideriv command
186
7.5 Interpolation
...................................................................................................................................
command
187
7.6 Baseline
...................................................................................................................................
Fitting & Subtraction command
188
7.7 Linear
...................................................................................................................................
Baseline Correction command
190
7.8 Data...................................................................................................................................
Point Removing command
191
7.9 Data...................................................................................................................................
Point Modifying command
192
© 2014 CH Instruments, Inc.
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CH Instruments Model 900D Series
...................................................................................................................................
193
7.10 Background
Subtraction command
7.11 Signal
...................................................................................................................................
Averaging command
194
7.12 Mathematical
...................................................................................................................................
Operation command
195
7.13 Fourier
...................................................................................................................................
Spectrum command
196
Chapter 8 Analysis Menu
197
8.1 Calibration
...................................................................................................................................
Curve command
198
8.2 Standard
...................................................................................................................................
Addition command
200
8.3 Data...................................................................................................................................
Report command
202
8.4 Time...................................................................................................................................
Dependence command
205
8.5 Special
...................................................................................................................................
Analysis command
207
Chapter 9 Sim Menu
209
9.1 Mechanism
...................................................................................................................................
command
210
9.1.1
9.1.2
9.1.3
9.1.4
9.1.5
9.1.6
Digital..........................................................................................................................................................
Sim ulation dialog box
211
Potentials
..........................................................................................................................................................
and Rate Constants dialog box
215
Concentration
..........................................................................................................................................................
and Diffusion Coefficients dialog box
216
Surface
..........................................................................................................................................................
Concentration dialog box
217
Concentration
..........................................................................................................................................................
at Equilibrium dialog box
218
Sim ulation
..........................................................................................................................................................
Variables dialog box
219
9.2 AC Impedance
...................................................................................................................................
Simulator and Fitting Program
220
9.3 CV Simulate
...................................................................................................................................
command
224
9.4 CV Fitting
...................................................................................................................................
command
225
Chapter 10 View Menu
227
10.1 Data...................................................................................................................................
Information command
228
10.2 Data...................................................................................................................................
Listing command
230
10.3 Equations
...................................................................................................................................
command
231
10.4 Clock
...................................................................................................................................
command
232
10.5 Toolbar
...................................................................................................................................
command
233
10.6 Add ...................................................................................................................................
or Remove Buttons command
234
10.7 Status
...................................................................................................................................
Bar command
235
Chapter 11 Help Menu
237
11.1 Help...................................................................................................................................
Topics command
238
11.2 Old Help
...................................................................................................................................
command
239
11.3 About
...................................................................................................................................
command
240
Chapter 12 Appendix
241
12.1 Cables
...................................................................................................................................
and Connections
242
12.2 Firmware
...................................................................................................................................
Update Instructions
244
12.3 Troubleshooting
................................................................................................................................... 245
© 2014 CH Instruments, Inc.
Contents
v
...................................................................................................................................
246
12.4 Maintenance
and Service
12.5 Limited
...................................................................................................................................
Warranty
247
12.6 Safety
................................................................................................................................... 248
12.7 Abbreviations
...................................................................................................................................
of Electrochemical Techniques
251
12.8 Model
...................................................................................................................................
400C Series Time-Resolved Electrochemical Quartz Crystal Microbalance
252
12.9 Model
...................................................................................................................................
600E Series Electrochemical Analyzer Techniques
255
12.10 Model
...................................................................................................................................
700E Series Bipotentiostat Techniques
256
12.11 Model
...................................................................................................................................
800D Series Electrochemical Detector Techniques
257
12.12 Model
...................................................................................................................................
920D Scanning Electrochemical Microscope
258
12.13 Model
...................................................................................................................................
1000C Series Multi-Potentiostat
260
12.14 Model
...................................................................................................................................
1100C Series Power Potentiostat / Galvanostat
262
12.15 Model
...................................................................................................................................
1200B Series Handheld Potentiostat / Bipotentiostat
264
12.16 Model
...................................................................................................................................
1550A Pico-Liter Solution Dispenser
265
12.17 Picoamp
...................................................................................................................................
Booster/Faraday Cage and Multiplexer
267
12.18 Amp...................................................................................................................................
Booster and Liquid/Liquid Interface Adapter
269
12.19 Accessories
................................................................................................................................... 270
© 2014 CH Instruments, Inc.
General Information
Chapter 1
General Information
This chapter contains general information about your instrument.
Introduction
Electrochemical
Techniques
Software Features
System Requirements
Hardware Specifications
© 2014 CH Instruments, Inc.
1
2
1.1
CH Instruments Model 900D Series
Introduction
The scanning electrochemical microscope (SECM) was introduced in 19891 as an instrument that could
examine chemistry at high resolution near interfaces. By detecting reactions that occur at a small
electrode (the tip) as it is scanned in close proximity to a surface, the SECM can be employed to obtain
chemical reactivity images of surfaces and to make quantitative measurements of reaction rates.
Numerous studies with the SECM have now been reported from a number of laboratories all over the
world and the instrument has been used for a wide range of applications, including studies of corrosion,
biological systems (e.g., enzymes, skin, leaves), membranes, and liquid/liquid interfaces. 2 The trapping
and electrochemical detection of single molecules by SECM has also been reported.
The model 900D/920D Scanning Electrochemical Microscope consists of a digital function generator,
bipotentiostat, high-resolution data acquisition circuitry, three-dimensional nanopositioner, positioner
controller, and a sample/cell holder, as shown in the Figure below. The three dimensional nanopositioner
has a spatial resolution of nanometers and allows a maximum traveling distance of several centimeters.
The potential control range of the bipotentiostat is ±10 V and the current range is ±250 mA. The
instrument is capable of measuring current in the picoampere range.
The model 900D/920D is designed for scanning electrochemical microscopy, but is also capable of
many conventional electrochemical techniques for convenience.
Model 900D uses a stepper motor positioner that can travel 50 mm with 8 nm resolution. The Model
920D combines the stepper motor positioner with a three dimensional closed-loop piezo positioner.
Model 900D/920D is an upgrade to the 900B/910B SECM. The stepper positioner has better linearity
and resolution (8 nm versus 100 nm) and longer travel distance (50 mm versus 25 mm). Also, waveform
generation and data acquisition are significantly faster. The waveform update rate can be 10 MHz and
© 2014 CH Instruments, Inc.
General Information
3
the sampling rate can be 1 MHz at 16-bit resolution, while maintaining low noise levels. AC
measurement techniques including electrochemical impedance spectroscopy have also been added.
Improvements also include very stable and accurate potential and current control, and dual-channel data
acquisition at high speed.
The instrument can be controlled by any PC running Windows 98 or higher. It is easy to install and use.
The user interface uses the classic Microsoft design, so if you are familiar with Windows applications,
you can likely use the software without referring at all to this user manual or the comprehensive, contextsensitive help files that are included with the instrument software. The commands, parameters, and
options have been written using terminology that most chemists are familiar with. A customizable toolbar
allows quick access to the most commonly used commands.
The instrument provides many powerful functions, such as straightforward file handling, extensive
experimental control, flexible graphics, various data analyses, and efficient digital simulation. Additional
features include macro commands, working electrode conditioning, color, legend and font selection, data
interpolation, visual baseline correction, data point removal, visual data point modification, signal
averaging, Fourier spectrum, and a convenient technique-specific electrochemical equation viewer.
This model series includes a USB port (default) and a serial port for data communication with the PC,
with hot-switching capabilities available on the rear panel of the instrument. Firmware is now stored in
flash memory, and as a result, instrument firmware upgrades can be downloaded electronically and
installed immediately, instead of the inconvenient shipment and installation of EPROM chips.
1. A. J. Bard, F.-R. F. Fan, J. Kwak, and O. Lev, Anal. Chem. 61, 132 (1989); U.S. Patent No.
5,202,004 (April 13, 1993).
2. A. J. Bard, F.-R. Fan, M. V. Mirkin, in Electroanalytical Chemistry, A. J . Bard, Ed., Marcel Dekker,
New York, 1994, Vol. 18, pp 243-373.
© 2014 CH Instruments, Inc.
4
1.2
CH Instruments Model 900D Series
Electrochemical Techniques
Scanning Probe Techniques
SECM Imaging: constant height, constant current, potentiometric
Probe Approach Curves
Probe Scan Curve: amperometric, constant current, potentiometric
Surface Patterned Conditioning
Sweep Techniques
Cyclic Voltammetry
Linear Sweep Voltammetry
Rotating Disk Electrode Voltammetry
Tafel Plot
Sweep-Step Functions
Step Techniques
Chronoamperometry
Chronocoulometry
Staircase Voltammetry
Tast Polarography
Differential Pulse Voltammetry and Polarography
Normal Pulse Voltammetry and Polarography
Differential Normal Pulse Voltammetry and Polarography
Square Wave Voltammetry
Sweep-Step Functions
Multi-Potential Steps
A.C. Techniques
A.C. Voltammetry and Polarography
Phase-selective A.C. Voltammetry and Polarography
Second Harmonic A.C. Voltammetry and Polarography
A.C. Impedance Spectroscopy
A.C. Impedance versus Time
A.C. Impedance versus Potential
Stripping Techniques
Linear Sweep Stripping Voltammetry
Differential Pulse Stripping Voltammetry
Normal Pulse Stripping Voltammetry
Square Wave Stripping Voltammetry
A.C. Stripping Voltammetry
Phase-selective A.C. Stripping Voltammetry
Second Harmonic A.C. Stripping Voltammetry
Controlled-Current Techniques
Chronopotentiometry
Chronopotentiometry with Current Ramp
Multi-Current Steps
Potentiometric Stripping Analysis
Amperometric Detection Techniques
Amperometric i-t Curve
Differential Pulse Amperometry
© 2014 CH Instruments, Inc.
General Information
Double Differential Pulse Amperometry
Triple Pulse Amperometry
Integrated Pulse Amperometric Detection
Other Techniques
Bulk Electrolysis with Coulometry
Hydrodynamic Modulation Voltammetry
Electrochemical Noise Measurement
Open Circuit Potential - Time
© 2014 CH Instruments, Inc.
5
6
1.3
CH Instruments Model 900D Series
Software Features
User Interface
Unicode tabbed-document application: compatible with 32- and 64-bit Windows
monolithic architecture: minimal installation footprint and portable design bypasses the Windows
registry
multiple instances: control multiple instruments by simply duplicating the program
customizable toolbar: quick access to your most frequently used commands
complete, intuitive environment: run experiments, analyze data, and generate plots all in the same
window
dock able toolbar: quick graphical access to the most commonly used commands
status bar: technique, file status, and command prompt
WYSIWYG graphics
comprehensive context-sensitive help
File Management
Unicode support: international file and folder names
open data files: read directly from binary or plain-text files
save data file: binary, plain-text formats for exporting data (e.g., to spreadsheet)
list data file
convert to text files: for exporting multiple data files
text file format
print present data
print multiple data files
print setup
Experimental Setup
technique: a large repertoire of electrochemical techniques
experimental parameters: extremely wide dynamic range
system setup: line frequency, potential/current axis polarities
hardware test: digital and analog circuitry diagnostic test
Instrument Control
run experiment: real time data display in most cases
pause/resume during run
stop running experiment
reverse CV scan direction during run
repetitive runs: automatic data save, signal averaging, delay or prompt
run status: stir, purge, smooth after run, iR compensation, RDE and SMDE control status
macro commands: edit, save, read, and execute any series of commands
open circuit potential measurement
work ing electrode conditioning before running experiment
analog filter settings: automatic or manual setting of i/V converter, potential, and signal filters
stripping mode: enable/disable, deposition potential and time, stir and purge conditions
cell control: purge, stir, cell on, SMDE drop collection, pre-run drop knock, and stabilizing capacitor
rotating disk electrode: rotation speed, on/off control during deposition, quiescent time, run, and
between runs
step functions: multiple cycles of step function generator, for electrode cleaning or other purposes
iR compensation: automatic and manual compensation, solution resistance, double layer
capacitance and stability test
SECM probe control: calibration and move probe in three dimensions
Graphical Display
© 2014 CH Instruments, Inc.
General Information
7
present data plot: data plot with header, filename, parameters, and results
re-scaling and labeling: axis expression, re-scaling, and text insertion
overlay plots: plot multiple data sets on the same graph for comparison
parallel plots: plot multiple data sets side by side for comparison
zoom in: visually selected zoom area
manual results: visually selected baseline
peak definition: shape, width, and report options
X-Y Plot: import arbitrary data sets
peak parameter plot: ip~v, ip~v1/2, Ep~log(v) plots
semilog plot: current-potential semilog plot
graph options: display or printer options, axis, parameters, baseline, results, grids, axis inversion,
axis freeze, axis titles, data sets, XY scales, reference electrode, header, and notes
color and legend: background, axis, grid, curves, legend size, thickness, and display intervals
font: font, style, size, and color of axis labels, axis titles, header, parameters, and results
copy to clipboard: for pasting graphics in third-party applications (word processors, etc.)
3d plotting (NEW): interactive visualization of impedance data and SECM results; Laplacian
smoothing, Delaunay triangulation, and stereoscopic 3D anaglyph imaging (no special video card or
display required)
Data Processing
smoothing: 5-49 point least square and Fourier transform
derivatives: 1st - 5th order, 5-49 point least square
numerical integration
convolution: semi-derivative and semi-integral
interpolation: 2× - 64× data interpolation
baseline fitting and subtraction: selectable fitting function, polynomial order and potential range for
best fitting and baseline subtraction; particularly useful for trace analysis
linear baseline correction: visually selected baseline, slope, and DC level compensation
data point removal
data point modification: visual data point modification
back ground subtraction: difference between two data sets
signal averaging: averaging multiple sets of data
mathematical operations: both X and Y data arrays
Fourier spectrum
Analysis
calibration curves: calculate the unknown concentration and the slope, intercept, and correlation of
the curve; plot the calibration curve; save and read the calibration data
standard addition: calculate the unknown concentration and the slope and correlation of the standard
addition curve; plot the standard addition curve; save and read the standard addition data
data file report: calculate the unknown concentration from saved data files based on user-defined
peak potential range, species, and calibration information; generate analytical report in text format; up
to four species of interest
time dependence: calculate the unknown concentration as a function of time from saved data files
based on user-defined peak potential range and calibration information; report and/or plot
concentration as a function of time
corrosion rate calculation
CV Simulation and Fitting
fast implicit finite difference algorithm
reaction mechanisms: 10 predefined mechanisms; in select models, any combination involving
electron transfer, first- and second-order chemical reactions
system: diffusive or adsorptive
© 2014 CH Instruments, Inc.
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CH Instruments Model 900D Series
maximum equations: 12
maximum species: 9
simulation parameters: standard redox potential, rate of electron transfer, transfer coefficient,
concentration, diffusion coefficient, forward and reverse chemical reaction rate constants, temperature,
electrode area, and experimental parameters
save simulation parameters
read simulation parameters
real-time display of simulation data, concentration profiles
dimensionless current
equilibrium data
automatic detection and calculation of over-determined equilibrium constants
AC Impedance Simulation and Fitting
visually equivalent circuit input
automatic equivalent circuit parameters fitting
View
data information: date, time, filename, data source, instrument model, data processing performed,
header and notes
data listing: data information and numerical data array
equations: convenient compilation of general and technique-specific equations
clock
toolbar
status bar
Help
comprehensive context-sensitive HTML help
on-the-fly switching between HTML help and legacy WinHelp
using help
about the application
© 2014 CH Instruments, Inc.
General Information
1.4
System Requirements
Operating System: Windows 98 / NT / Me / 2000 / XP / Vista / 7 / 8
Communication between PC and instrument: USB or RS-232 serial port
Output device: any printer or plotter supported by Windows
© 2014 CH Instruments, Inc.
9
10
1.5
CH Instruments Model 900D Series
Hardware Specifications
Micropositioner:
Piezo positional resolution:
1.6 nm
Stepper motor resolution:
4 nm
X, Y, Z total distance:
50 mm
Bipotentiostat:
Probe Potential:
±10 V
Substrate Potential:
±10 V
Current: ±250 mA
Compliance Voltage:
±12 V
Input Impedance of Reference Electrode: 1012 Ω
Current Measurement Range: 10-12 - 0.1 A/V in 12 ranges
Low Current Measurability: 1 pA
Maximum Sampling Rate: 1 MHz (16-bit)
Waveform update rate:
10 MHz maximum
Cell Control: purge, stir, and knock
RDE Rotation Rate Control: 0-10V voltage output for 0 - 10000 rpm
Other Features:
External voltage input recording channel
Automatic and manual iR compensation
© 2014 CH Instruments, Inc.
Getting Started
Chapter 2
Getting Started
This chapter contains information about how to get started using your instrument.
Installation
Testing
Some Useful Tips
USB Driver Installation
© 2014 CH Instruments, Inc.
11
12
2.1
CH Instruments Model 900D Series
Installation
Important Note
After you unpack the instrument, please check the contents of the shipment carefully. You should find
the instrument, USB cable, electrode leads, software CD, and a printed copy of this User Manual
(optional). Electrodes and other accessories are sold separately; if you ordered electrodes and
accessories, please thoroughly check the shipment and compare its contents with the packing list. If
anything is missing, please search thoroughly inside the container, since the missing items may have
been mixed with the packing material over the course of shipping. Please report any missing or
damaged items immediately and do not throw away the shipping materials, as these may be used for
return shipping.
© 2014 CH Instruments, Inc.
Getting Started
2.1.1
13
Parts List
The CHI900D series SECM comes with the following parts:
Part #
Item
CHI900D Bipotentiostat
CHI900D Motor controller
Stepper motors with translation stages
3' 15F-15M cable for stepper motor control
Z-Stand
Piezo Positioner (CHI920D only)
Mounting Piece for Z stage or Piezo positioner (Black T-shaped)
Base, Sample holder
Probe holder (Teflon)
Mounting piece for probe holder
Nylon screws for piezo calibration
Nylon washers for piezo calibration
Brass pin with 10K ohm resistor for piezo calibration
Teflon cell with Pt wire counter electrode (for insulator substrate) with O-ring
Teflon cell with Pt wire counter electrode (for conducting substrate)
CHI303 Pt disk electrode (as conducting substrate) with O-ring
CHI304 Ag/AgCl reference electrode
CHI116 10 mmm Pt disk probe
Tools (wrenches)
User manual (electronic copy)
Power cord
6' USB A/B cable for communications
3' 25F-25M cable for connections between bipotentiostat and motor controller
Electrode leads
Software CD
Quant.
1
1
3
3
1
1
1
1
1
1
4
4
1
1
1
2
2
3
1
1
2
1
1
1
1
Please examine the contents of your shipment carefully and immediately report any missing parts to CH
Instruments, Inc..
© 2014 CH Instruments, Inc.
14
2.1.2
CH Instruments Model 900D Series
Software
The instrument can be controlled by any PC running Windows 98 / NT / Me / 2000 / XP / Vista / 7 / 8. A
free USB port or serial port is required for communication between the instrument and the PC. Refer to
your Windows system documentation to gain familiarity with Windows operation.
Windows Vista can control the instrument properly, but will sometimes can experience graphical
glitches. The program may paint single pixel dots incorrectly or leave entire areas of the screen blank.
Choose other legends (such as circle, square, triangle or line) to plot data correctly. These glitches
appear endemic to Vista and do not occur in versions of Windows older or newer than Vista.
The software in-program documentation has been upgraded to compressed HTML (.chm) files, which
provide comprehensive context-sensitive help via the Shift+F1 keyboard shortcut and in dialog boxes.
Legacy documentation is also available in Microsoft's old WinHelp (.hlp) file format, and the program can
switch dynamically between .chm and .hlp files when the latter are available. This is particularly useful
when using newer software versions with older instrument models. However, our old WinHelp files may
be out of date, and their use is discouraged. Moreover, starting with Windows Vista, Microsoft has also
dropped out-of-the-box support for 32-bit .hlp files (although strangely, 16-bit .hlp files from the Windows
3.x era are still supported). This issue can be resolved by installing WinHlp32.exe from the Microsoft
website; refer to article KB917607 for more information.
To install the software, insert the software CD. Double-click the "set####.exe" file on the CD to extract
the files to your hard drive. The default extraction directory is C:\CHI. The installation simply copies all
files to the extraction directory. After installation, you should find chi####.exe (the program executable),
chi####.chm (HTML help file), and some test data files (*.bin) in this directory. Administrative rights are
not required to run the program, and UAC permissions introduced in Vista should not be an issue. If the
executable is copied or moved (say, to D:\My.Prog.exe) it must be accompanied by a help file with the
same name (say, D:\My.Prog.chm) for the comprehensive context-sensitive help to be available.
The program has been designed with ease of use in mind. It is self-contained and portable.
Double-click chi####.exe to start the program. The only file required to run the software and control the
instrument is chi####.exe, which can be placed in any directory for which you have write and execute
permission. This can be particularly useful in restricted user settings (teaching labs, portable
installations on removable media, etc.)--simply copy the .exe file and .chm file to, say, the user's home
directory.
The first time it is run, the program will automatically generate a binary configuration file (chi####.cfg)
containing (virtually) all user preferences and settings. This configuration file will have the same name
and location as the executable, and multiple instruments can be controlled using multiple copies of the
executable, each with its own configuration file (e.g., chi660d1.exe + chi660d1.cfg and chi660d2.exe +
chi660d2.cfg). Newer versions of the software will also generate chi####.ini, which harkens back to a
kinder, gentler time when ini files ruled the electronic earth, untrammeled by the unreliable tyranny of the
registry. Even now, our software avoids the registry completely, storing all settings in the .cfg and .ini
files, streamlining the transfer of user settings between directories or computers to a simple file copy
operation.
In previous versions of the software, the auto-generated configuration files would be stored in the C:\CHI
directory, and if this directory was not found, the configuration files would be annoyingly spread
everywhere. This behavior should not occur in the current software version, and it should be safe to
extract the program to any directory on any drive or partition for which you have write and execute
permission.
© 2014 CH Instruments, Inc.
Getting Started
15
To uninstall the software, simply delete all program files: the executable (.exe), help (.chm and .hlp if
present), and configuration (.cfg and .ini). Since no settings are stored on the registry, an uninstaller is
unnecessary.
The software CD also contains a hyperlinked, electronic copy of this User Manual and the USB Driver. In
addition, you can find a Lab Manual from the 2003 SECM Summer School at the University of Texas at
Austin. Note that an older model 900 SECM was used in the Summer School; nevertheless, it contains
quite a bit of information that you may find useful.
© 2014 CH Instruments, Inc.
16
2.1.3
CH Instruments Model 900D Series
Hardware
System hardware installation is also easy and simple. After unpacking the instrument, you should
check your power lines. The AC voltage of the instrument was preset in the factory and is
indicated on the serial number label on the back panel. If the AC voltage is correct, connect the
instrument to the power with the power cord.
There are two instrument boxes; you can stack them on top of each other as shown in Figure 2.1. The
box with three DA-9 connectors, a 4-pin round connector, and a DA-15 connector on the front panel is
the stepper motor and piezo controller. Connect the stepper motors to the 15-pin DA connectors labeled
"Stepper", labeled from left to right for the X, Y, and axes. For the model 920D, also plug connect the
piezo to the 4-pin round connector labeled "Piezo" and the sensor to the 15-pin DA connector. The other
instrument box contains the bipotentiostat, digital function generator and data acquisition circuitry. You
need to connect the two boxes together, plugging the 3-ft DB-25 cable into the two connectors labeled
"Cell Control" on their rear panels.
Figure 2.1. Front and rear view of the instrum ent chassis for the stepper m otor/piezo controller (bottom ) and
bipotentiostat (top).
It is recommended to power the bipotentiostat on first. Turn the motor controller off first when powering
down the system. It is recommended to keep the motor controller turned off when the piezo block is not
going to be used in the next hour or longer (model 920D). The bipotentiostat can still be used when the
motor controller is turned off, and this will extend the lifetime of the piezo.
For model 920D, please make sure that the motor controller is turned off when powering up or
powering down the bipotentiostat. Otherwise, very high voltages will be applied to the piezo block,
greatly reducing the lifetime of the piezo.
The instrument communicates with the PC through an RS-232 serial port (default) or USB port (but not
both). If your computer has a free serial port (9-pin male connector), it can directly communicate with the
instrument without installing any drivers using a 9F-25M serial cable (not included). You may need to
change the instrument software com port setting (default COM1) using the System command under the
Setup menu. You don’t have to worry about the baud rate. After changing the COM port setting, exit and
re-launch the program.
If you have a free serial port available on your PC, we recommend its use over a USB port. This is
because we implement USB connectivity using a USB-to-serial chip on the instrument, i.e., a physical
USB port is used on the PC, but the USB data are converted to serial by the driver software supplied by
the USB chip vendor.
© 2014 CH Instruments, Inc.
Getting Started
17
USB communication is achieved using a USB-to-serial chip built into the instrument, allowing serial
communication to occur through the USB port using drivers provided by the chip vendor. It therefore
provides no specific advantages over the serial port besides the difference in physical connectivity, and
both the instrument and the PC will interact as if connect by a serial connection. The reason we include
USB support is that newer computers may not include a serial port, and it may be impractical or
impossible to add a serial port card.
To use a USB port for data communication, you must first install the USB driver (included on the
software CD; also available from www.chinstruments.com). Depending on your model, you may also
need to change a jumper setting inside the instrument (see below).
If there is no available serial port on your computer, you can use a USB port for communication instead.
To do so, you need to change a jumper setting inside the instrument (Figure 2.2) and install the driver
software on your PC.
Figure 2.2 Serial port or USB port sw itch selection using tw o jum pers (indicated by arrow s). Left: RS-232
serial port jum per setting. Right: USB jum per setting.
USB driver installation will be described in detail later in this chapter.
If you consistently encounter "Link Failed" messages, try a different PC. The instrument we delivered
was turned on for a week and tested. In nearly all cases, consistent "Link Failed" messages are caused
by the PC, either by port settings or problems.
You may occasionally notice unreliable data communication. This could be due to background tasks
that generate interrupts, since serial port data communication is interrupt-based. In recent versions,
Microsoft Windows has lowered the priority of the serial port interrupt. Other devices, such as disk
access, screen saver, virus scan, internet connection, etc. will all generate interrupts that could interfere
with the serial port data communication. Please disable your screen saver, disconnect from the internet,
disable any virus scanners, and try again.
You should also not use a network card, which will generate a background interrupt that interferes with
data transfer between the PC and the instrument. Disconnect the connector to the network card.
If you continue to encounter get "Link Failed" messages after all these efforts, please try a different
computer.
Once the instrument and PC can communicate properly, you can connect the electrode leads to the rear
panel. The green clip is for the working electrode, white is for reference, and red is for counter. The black
clip is a sensing electrode.
© 2014 CH Instruments, Inc.
18
CH Instruments Model 900D Series
The Cell Control port on the rear panel is used for stepper and motor control when the nanopositioner is
used for SECM or other scanning probe techniques. This port can also be used to control purge, stir,
and mercury drop dislodge. Please see the Appendix for more information.
If you have a Pine Instrument AFMSRX or AFMSREC Rotator for RDE, it is possible for the instrument to
control the RDE with the instrument (select models). Two banana jacks on the rear panel will provide a
voltage of 0 - 10 V, corresponding to a rotation rate of 0 - 10,000 rpm.
This instrument is also capable of controlling a Pine Instrument AFMSRX or AFMSREC Rotator for RDE.
Two banana jacks on the rear panel will provide a voltage of 0 - 10 V, corresponding to a rotation rate of 0
- 10,000 rpm.
© 2014 CH Instruments, Inc.
Getting Started
2.1.4
19
Nanopositioner, Stepper Motors, and Piezo
Nanopositioner Assembly
Figure 2.3. Nanopositioner and Cell/sam ple holder
When the instrument is shipped, all stages are dismounted. Please carefully follow the instruction
video included on the software CD to assemble the positioner. Follow the video exactly to
assemble the nanopositioner and cell/sample holder as shown in Figure 2.3. Please call or e-mail us if
you have any questions. Make sure not to unscrew the screws that are part of the stages. The X Y Z
stages will all be mounted on top of the supporting stainless steel plate, with the Y stage under the X
stage. The cell/sample holder will also be mounted to the stainless steel base.
First, mount the Z stage on the Z stand. Tighten the four cap screws on the rear panel of the Z stand. Be
sure to place the Z stage as high as possible. This is important. Otherwise, when the Z stage moves
© 2014 CH Instruments, Inc.
20
CH Instruments Model 900D Series
down, it will collide with the Y stage. This may cause the motor to stop and lose track of its position, as
well as reducing the travel distance for the Z stage.
Next, stack the Z stand on the X stage plate. Use four cap screws to secure the Z stand to the X stage.
The front edge of the Z stand should be aligned with the front edge of the X stage and not recessed in at
all, to ensure that when the Z stage does not collide with the X stage when it moves up and down.
Please note that the positive direction for the X axis is to the right. The positive direction for the Y axis is
to the front. The positive direction for the Z axis is downward.
For the 920D, once all three stages are mounted, you need to mount the XYZ piezo block to the Z stage.
The piezo mounting piece, piezo positioner, and tip holder are shipped pre-assembled. Use two 5 mm
cap screws to mount the T-shaped mounting piece with the XYZ piezo block to the middle row of the Z
stage.
The cell/sample holder should be mounted on top of the bottom supporting stainless steel plate, with a
rectangular plate on top of the columns. You can put the cell and sample on the plate for
measurements. If you want to adjust the tilt level of the cell and sample, you can mount three fine
adjustment screws on the rectangular plate and put the T-shaped stainless steel plate on top of those
fine adjustment screws. Each turn of screw corresponds to 317 µm. The resolution is 1 µm.
On both the rectangular and T-shaped plates, there is a hole for a round plate or a ring. The round plate
and ring are interchangeable. Insert the platinum disk working electrode into the ring to use it as a
conducting substrate electrode. Alternatively, you can use the round plate to hold other samples. Use a
rubber O-ring to seal the sample and cell holder to prevent leakage. The Teflon cell should be mounted
on the rectangular or T-shaped plate using screws.
You may want to change the line frequency program setting (60 Hz or 50 Hz) using the System
command under the Setup menu. This will set the default sampling period to a multiple of the reciprocal
line frequency when applicable, which will help to reduce noise.
Connecting the stepper motors and XYZ piezo block
Use 15M-15F extension cables to connect the stepper motors to the 15-pin DA connectors labeled
"Stepper" on the front panel (marked for the X, Y, and Z axes from left to right). You should use the 3 ft
15M-15F extension cables included with the instrument. Other cables may have too high resistance,
which can cause serious errors in motor control.
To connect the piezo block to the controller, simply connect the 4-pin round plug to the 4-pin round
connector labeled "Piezo" on the front panel of the motor controller. Please be advised that there are
high voltages in the round connector. You also need to connect the sensor connector to the front panel.
Understanding the piezo block
The piezo lifetime depends essentially on the amplitude of the voltage applied to the piezo and how long
a high voltage is applied. At highest voltage (150V for this piezo), the lifetime is about 1000-1500 hours,
or 125-200 days for average usage of 8 hours per day. At 50V, it will last 30,000 hours or about 10
years. It is recommended to keep the motor controller turned off when the piezo block is not going to be
used in the next hour or longer. It is also recommended to image by scanning X and Y from zero in the
positive direction. At the end of imaging, set the tip to return to the origin. This will ensure low piezo
voltage between experiments, extending the lifetime of the piezo, which is a relatively expensive part to
replace.
© 2014 CH Instruments, Inc.
Getting Started
21
The program will issue a warning if a high piezo voltage is detected for too long. If this happens, you
should either move the piezo back to zero or start the next experiment.
© 2014 CH Instruments, Inc.
22
2.2
CH Instruments Model 900D Series
USB Driver Installation
Part 1: Driver Installation
System Requirements
Windows XP / Vista / 7 / 8
CH Instruments Software version 12.04 or newer
If your system does not meet the requirements above, please visit our website for instructions and
downloads for all versions of Windows, starting from Windows 98.
Installation Procedure
1. Do not connect the instrument to the computer yet.
2. Double-click the USB Driver installer on your software CD.
3. Follow the on-screen instructions, accepting all default options in the affirmative.
- Make sure the "Launch the CP210x VCP Driver Installer" option is checked, when it appears.
- This should install files in two locations.
- Restart your computer if prompted to do so.
4. Finally, power on and connect your instrument to your computer. Windows should now recognize the
instrument automatically.
5. Please note that the latest driver requires our software version 12.04 or newer.
Part 2: Instrument Installation
Installation Procedure
1.
2.
3.
4.
5.
6.
Complete the USB Driver Installation Procedure from Part 1 above.
Disconnect the instrument from your PC, if applicable.
Connect the instrument to your PC and turn the power on.
Wait for any automatic system installation tasks to complete.
Open Device Manager (right-click [My] Computer > Manage > Device Manager).
Double-click the category "Ports (COM & LPT)" to display:
© 2014 CH Instruments, Inc.
Getting Started
23
7. Determine the COM number for the newly installed "CP2101 USB to UART Bridge Controller" or
similarly named device.
- In the figure above, this is COM5.
8. Assign this COM number using the System command under the Setup menu in our software.
9. Run the Hardware Test command under the Setup menu to confirm that the instrument and computer
are communicating properly.
This completes instrument installation.
Part 3: Additional Information
In the future, if you encounter the “Can not open com port” message when starting the program, please
check Device Manager again and see what com port number is currently assigned to the instrument. If
the com port number assignment has changed, you need to set the com port number using the System
command accordingly. If you do not see the CP2101 device listed in under Ports (COM & LPT), please
make sure your instrument is turned on and the USB cable is properly connected.
The USB driver needs to be installed only once on your computer. Multiple instruments can be
connected to the same computer, and Windows automatically assign them to different COM ports.
USB communication is achieved using a USB-serial port converter chip inside the instrument. Our
software will behave as if this device is connected to a serial port, even though the physical connection
is by USB. Thus, you need to use Device Manager as described above to determine what serial port
number is assigned to this device.
You can double-click on the "CP210x USB to UART Bridge Controller" item in Device Manager to
display various status information: driver version number, whether the driver is functioning correctly, etc.
If you have a free serial port available on your PC, we recommend its use over a USB port. This is
because we implement USB connectivity using a USB-to-serial chip on the instrument, allowing serial
© 2014 CH Instruments, Inc.
24
CH Instruments Model 900D Series
communication to occur through the USB port using drivers provided by the chip vendor. USB therefore
provides no specific advantages over the serial port besides the difference in physical connectivity, and
both the instrument and the PC will interact as if connected by a serial connection. The reason we
include USB support is that most computers sold today do not include a serial port, and it may be
impractical or even impossible to add a serial port card.
However, the supplied third-party USB-serial port drivers may not be perfect. We have tested them on
several computers in our office and they all seem to work, but if problems occur, since the Windows
drivers are closed-source, we have no way to modify, let alone debug them. Our only recourse in that
scenario would be to file a support ticket with the chip vendor, and it may prove more expedient to buy a
USB to Serial Adapter cable and a DB-25 male to DB-9 female cable (each ~$10 USD at the time of this
writing).
Depending on your instrument model, you may also need to set the USB/serial selection switch inside
the instrument (see Figure 2.2 above) to the appropriate setting.
For more information, please visit <www.chinstruments.com/downloads.shtml>.
© 2014 CH Instruments, Inc.
Getting Started
2.3
25
Testing
The instrument was thorougnly tested by our quality assurance team before it was shipped. The "*.bin"
files included on the software CD are the data actually acquired with the particular instrument you
received.
To test communication between the computer and the instrument, start the software and turn the
instrument on. Use the Hardware Test command under the Setup menu. If a “Link Failed” error appears,
should check the connection and port settings. Use the System command under the program Setup
menu to see if the port setting matches the port in use.
If hardware test results appear on the screen, the PC-instrument communication is working properly. The
hardware test results will provide further details regarding the status of your instrument.
To test hardware performance, you can use (say) a 100K ohm resistor as a dummy cell. Short the
reference (white) and counter (red) electrode leads and connect the 100K ohm resistor between the red/
white clips and working (green) electrode clip. Select the potential range to be 0.5 V to -0.5 V using the
Parameters command under the Setup menu. The sensitivity can be set to 1e-6 A/V. Run the
experiment using the Run command under the Control menu. You should observe a straight line with
current from -5e-6 A to +5e-6 A.
To test software performance, open a data file using the Open command under the File menu to open
the test data files included on the software CD. These are the actual test results for this particular
instrument. To open the files, select the files and click OK, or double-click the filename. After reading
them in, you can display or process the data. Try the commands under the Graphics and DataProc
menus. To revert to the original data and undo all unsaved changes, simply close the file and reload the
data with the Open command.
When you assemble the SECM as shown in Figure 2.3 above, you need to calibrate the piezo first for
model 920D. Use the SECM Probe command under the Control menu (see Chapter 5).
To test the SECM, it is suggested to use 1 mM ferrocenemethanol in 0.1M KNO3. Ferrocenemethanol
can be purchased from Aldrich Chemical Co. It is water soluble and its redox reaction is reversible. It is
better than ferricyanide or rutheniumhexamine and gives more reproducible data. The curve is flatter in
the diffusion-limited region. Moreover, the electrode surface will not be contaminated, whereas
ferricyanide reaction products may adsorb to the surface of the electrode, decreasing current flow over
time.
First mount the platinum disk substrate electrode onto the SECM cell. The substrate electrode can be
inserted into the metal ring. Insert the substrate electrode into the bottom of the Teflon SECM cell. You
will need to insert a rubber O-ring between the Teflon cell and the metal ring to avoid leakage. Screw the
Teflon cell to the stainless steel plate. Usually the counter and reference electrodes will be on the right
side when viewed from the front. Pour the solution into the cell. Insert the reference electrode into the
hole on the Teflon cell wall. Insert the tip into the tip holder.
You need to move the tip close to the substrate surface. Initially you should use the SECM Probe
command under the Control menu. You will find the XYZ move command at the bottom-left of the dialog
box, which moves the tip fairly fast. Make sure sure it does not get too close to the surface. If the tip
touches the surface, the surface will be damaged (fortunately, the 10 um tip will not be damaged so
easily). On the other hand, you do not want the tip to be too far away from the surface, because the
following Probe Approach Curve experiment moves the tip rather slowly.
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CH Instruments Model 900D Series
Once the tip is reasonably close to the surface, you can use the Probe Approach Curve technique to
bring the tip closer to the surface. You can set experimental parameters using the file PACxx.bin
included on the software CD. For ferrocenemethanol, the tip is held at an oxidation potential
around +0.5V vs. Ag/AgCl. The substrate potential is held at a reduction potential around 0 V vs. Ag/
AgCl. If the tip is over the insulating part of the surface, current will drop as the tip approaches the
surface. If the tip is over the conducting part of the substrate, current will increase as the tip gets
approaches the surface. Tip approach will stop when the specified threshold current ratio or level is
reached. The threshold current ratio should be less than 100% for insulators and greater than 100% for
conductors; if the current ratio is improperly specified, approach will stop at a current ratio of 75% or
125%.
Once the tip is close to the surface, you can use the Probe Scan Curve (PSC) technique to scan across
the sample surface. For a platinum substrate electrode, it is useful to find the boundary between the
insulator and the conductor. A good test is to image this boundary. If the tip is close to the leftmost
boundary, a standard SECM scan of 80 µm 80µm using X as the long axis should reveal a vertical
boundary because your scan area is much smaller than the curvature of the disk electrode. If you move
the tip to the frontmost edge and image using Y as the long axis, you should see a horizontal boundary
line.
Check your PAC, PSC, and SECM images to verify the correct operation of your SECM instrument.
These are not very exciting images or curves, but they constitute a good test of the instrument.
© 2014 CH Instruments, Inc.
Getting Started
2.4
27
Some Useful Tips
If you are comfortable with Windows applications, you may not have any problem using the instrument.
Most of the following tips are intended for users who do not have much experience with Windows, but
may still be useful even for experienced users.
1. Familiarize yourself with with the toolbar (the bar with many buttons under the main menu bar), which
provides quick access to the most commonly used commands. Hover the mouse cursor over a button
without clicking to display a descriptive comment in the lower-left corner of the main window.
2. To select multiple filenames for multiple file printing, overlay plots, parallel plots, etc., left-click on the
name of the first file you want to select and drag the mouse while holding the left button to select
multiple files. If the files you want are scattered in the directory (i.e., non-consecutive), you can select
them by holding down the Ctrl key and clicking on each filename.
3. If the Y axis title is oriented in the wrong direction, use the Font command under the Graphics menu
to change the rotation angle of the Y axis for printing.
4. To select a file or technique, you can double-click the item. This is equivalent to clicking the item and
then click OK.
5. To change parameters in a dialog box, you can use the Tab key to cycle through its fields. Text in the
edit box will become highlighted, and you can type directly to replace the highlighted text. This can
sometimes be much more convenient and faster than using the mouse. Advanced users should also
consider memorizing frequently used keyboard shortcuts (press the Alt key to move focus to the
menu bar, then type underlined letters to enter menus and run commands).
6. The internal noise of the instrument is quite low. The most common and most serious source of noise
is the line frequency (60 Hz or 50 Hz). The instrument contains analog low-pass filters to reduce this
noise. At a scan rate of 0.1 V/s, the automatic filter cutoff setting is 150 or 320 Hz, which does not
cover the line frequency, but at a scan rate of 0.05 V/s, the cutoff frequency of the filter is 15 or 32 Hz,
and the line frequency noise can be effectively reduced. Line frequency noise can also be reduced if
the sampling interval is set to a multiple of the period of the power line. For small signals or relatively
fast experiments, use of a Faraday cage is strongly recommended.
7. Use the Graph Options command under the Graphics menu to adjust the way data is displayed; see
Chapter 6 for more information on the wide variety of options available.
8. The latest version of the software includes interactive 3D graphics for visualizing SECM data. You can
also generate a 3D surface plot with the SECM image data in Microsoft Excel by converting the data
to text format. First use the Text File Format command under the File menu and check the Excel 3D
Format box. Consult the context-sensitive Help in the Text File Format dialog box to read the
procedures for making Excel 3D surface plot.
© 2014 CH Instruments, Inc.
File Menu
Chapter 3
File Menu
The File menu offers the following commands:
New
Open
Close
Save As
Delete
Retrieve
Update Instrument Prog.
List Data File
Convert to Text
Text File Format
Import Text File
Print
Print Multiple Files
Print Preview
Print Setup
Send...
Most Recently Used
Exit
© 2014 CH Instruments, Inc.
Creates a new document.
Opens an existing document or text file.
Closes an opened document.
Save current document; can convert to plain text, csv.
Delete existing data files permanently (legacy command).
Retrieve lost experimental data.
Update instrument firmware.
Display an existing data file in text format.
Convert multiple existing data files to text files.
Choose text file formatting options.
Import text file (legacy command superseded by Open).
Prints a document.
Print multiple documents.
Displays the document on the screen as it would appear printed.
Selects a printer and printer connection.
Sends the active document through electronic mail.
Open the most recently used documents quickly.
Exits the program.
29
30
3.1
CH Instruments Model 900D Series
Open command
This command opens the File Open dialog box.
Use this command to open one or more existing documents each in a new window. You can open
multiple documents at once. The program displays the File Open dialog box so you can select the files
you want to convert.
Binary data files and text files saved from the program can both be read directly by this command, which
fully supersedes the Import Text File command.
When a file is read, the program places its data in memory and updates the display, technique, and
experimental parameters (some of which are only available in binary data files). You can only open files
generated by this or an older version of the software.
Use the Window menu to switch among the multiple open documents. See Window 1, 2, ... command.
You can create new blank documents with the New command.
This command has a toolbar button:
The Open command presents this dialog box.
Binary data files and text files saved from the program can both be read directly by the Open command,
which fully supersedes the Import Text File command.
The following options allow you to specify which file to open:
File name
Type or select the name of the file(s) to be opened. The box above lists files with the extension you
select in the "Files of type" box. You don't have to type the extension; the program will automatically
attach the selected extension in the "Files of type" box to the filename (or the default “.bin” if All Files (*.
*) is selected). Multiple file names in the "File name" field are enclosed by quotation marks and
© 2014 CH Instruments, Inc.
File Menu
separated by spaces, for example, "CV0" "CV1".
Files of type
Specifies the type of file you want to open (by default, all files are displayed):
Extension
.bin
.txt
.csv
Description
Binary data files
Plain text files
Comma-separated value files
© 2014 CH Instruments, Inc.
31
32
3.2
CH Instruments Model 900D Series
Save As command
This command opens the File Save As dialog box.
Use this command to save and name the active document. The program displays the Save As dialog
box so you can name your document.
When a non-binary file type is selected, this command allows you to perform the Convert to Text
operation on the currently active data file without having to navigate to the file.
This command has a toolbar button:
The Save As command presents this dialog box.
The following options allow you to specify the name and location of the file you're about to save:
File name
Specifies a file name to save the current data and system variables with a different name. You don't have
to type the extension; the program will automatically add the extension you specify in the "Save as
type" box. If an existing filename is used, the system will display a confirmation prompt before
proceeding.
Save as type
Specifies the type of file you want to save as. When saving in the ".txt" or ".csv" formats, a
corresponding ".bin" file will be generated unless a binary file is currently open. The use of binary files is
encouraged, since they contain many system parameters that are not stored in other formats.
Extension
.bin
.txt
.csv
Description
Binary data files (recommended)
Plain text files (compatible with most other programs)
Comma-separated value files (useful for spreadsheet programs)
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File Menu
33
For a macro file, the extension is ".mcr". For a simulation file, the extension is ".sim". Other extensions
are not allowed.
© 2014 CH Instruments, Inc.
34
3.3
CH Instruments Model 900D Series
Delete command
Use this deprecated command to delete files permanently via the File Delete dialog box.
The Delete command bypasses the Recycle Bin that has been available starting with Windows 95, and
its use is discouraged for all but the audacious and the accustomed.
To send one or more files to the Recycle Bin (unless it has been disabled in your Windows system
settings), in the CHI program environment, select the desired file(s) in the, say, Open or Save As dialog
box and press the Del key. Windows will then prompt you for confirmation to send the file(s) to the
Recycle Bin. To delete files permanently in the same manner, press Shift+Del instead of Del.
The deprecated Delete command presents this dialog box.
The following options allow you to specify the name and location of the file you're about to delete
permanently:
File name
Type or select the filename(s) you want to delete permanently. You don't have to type the extension; the
system will automatically attach the selected extension in the "Files of type" box to the filename. The
box above lists files with the extension you select in the "Files of type" box. To delete multiple files
permanently, point the mouse cursor to the files you want to select and click the left mouse button while
holding down the Ctrl key.
You will be prompted for confirmation before the files are deleted permanently.
Files of type
Select the type of file you want to delete permanently.
© 2014 CH Instruments, Inc.
File Menu
3.4
35
Retrieve command
Use this command to retrieve data saved on the PC hard drive during an experimental run. In case your
experiment does not run to completion, e.g., due to external interference, interruption, or missed
communication, data can be recovered partially. This is useful for very slow experiments; hours of
experimental data can be recovered.
For performance reasons, this command is not enabled by default. For fast experiments, it may prove
more expedient to simply re-run the experiment instead of using the Retrieve command. In order to
enable the Retrieve command, use the System command under the Setup menu and check the "Save
retrieve data during run" option.
Data from the previous run must be retrieved before starting a new run. Once a new run has started, the
saved data for the last run will be lost and cannot be recovered.
© 2014 CH Instruments, Inc.
36
3.5
CH Instruments Model 900D Series
Update Instrument Program command
This command opens the Firmware Update dialog box.
Control of the instrument control is accomplished by two interacting components: the software that
resides on the PC, and the firmware that resides on the instrument. This command, available in all of our
newer models with flash memory, allows the user to install firmware updates, which are issued
occasionally by CH Instruments, Inc.. For more information about software and firmware updates, please
consult the Appendix of this User Manual or contact [email protected]
© 2014 CH Instruments, Inc.
File Menu
3.6
37
List Data File command
This command opens the List Data File dialog box.
Use this command to display a saved data file in text mode. Formatting options are available in the Text
File Format command.
The current data remains unchanged when this command is executed. To view the current data similarly,
use the Data Listing command under View menu.
The List Data File command presents this dialog box.
The following options allow you to specify the name and location of the file you're about to display in text
mode:
File name
Type or select the filename you want to display. The box above lists files with the extension you select
in the "Files of type" box.
You don't have to type the extension. The system will automatically attach an extension of ".bin" to the
filename. Other extensions are not allowed.
Files of type
Select the type of file you want to list. Only ".bin" files (binary data) are available.
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3.7
CH Instruments Model 900D Series
Convert to Text command
This command opens the File Conversion dialog box.
Use this command to convert one or more binary data files to text (the format can be altered with the
Text File Format command in the File menu). The program displays the File Conversion dialog box so
you can select the files you want to convert.
The resulting text file can be read by other software, such as commercial spreadsheet or database
handlers.
The Convert to Text command presents this dialog box.
To select multiple files for conversion, point the mouse cursor to the filenames you want to select and
click the left mouse button while holding the Ctrl key, or left-click on two files while holding the Shift key
to select a range of files, or left-click and drag. To quickly convert the currently active file, use the Save
As command instead.
The following options allow you to specify the name and location of the binary file(s) that will be
converted to text format:
File name
Type or select the filename(s) you want to convert. The box above lists files with the extension you
select in the "Files of type" box.
Multiple files can be selected for conversion.
You don't have to type the extension. The program will automatically attach an extension of ".bin" to the
filename. Other extensions are not allowed.
Files of type
Select the type of file you want to convert. Only the ".bin" type (binary data file) will be available.
© 2014 CH Instruments, Inc.
File Menu
3.8
39
Text File Format command
This command opens the Text File Format dialog box.
Use this command to specify text formatting options for non-binary files generated by the Save As and
File Conversion commands.
The Text File Format command presents this dialog box.
Memo
Check this box to include date, time, technique name, labels, and notes in the output text file.
Parameters
Check this box to include experimental parameters in the output text file.
Results
Check this box to include experimental results such as peak/wave potential, current, and electrode area
in the output text file. To select the item to be displayed on screen when an experiment is complete,
execute the Peak Definition command in the Graphics menu.
Numeric Data
Check this box to include numeric data points in the output text file.
© 2014 CH Instruments, Inc.
40
CH Instruments Model 900D Series
Separator
Select the separator (comma, TAB, space, or linefeed) to be used between data columns. For two data
points X and Y, the resulting output will be:
Separator
Comma
TAB
Space
Linefeed
Output
X, Y
X
Y
XY
X
Y
This allows you to make the data format compatible with other commercial software, such as
spreadsheet or database handlers.
Number of Significant Figures
This option allows you to set the data precision of the text file up to a maximum of 10 significant digits
(figures). A larger number of significant digits will of course result in larger data files. The default setting
of 4 significant digits is sufficiently precise for most applications.
Data Point Interval
This option allows you to store or display a subset of the data points. For example, when the value is
changed to 3, only every 3rd data point will be stored or displayed. This option is useful for quick
examination of data or file size reduction. However, some details might be lost.
DigiSim Format for CV and LSV Data
This option applies only to CV and LSV data. When this box is checked, the text data file will be directly
readable by DigiSim (© Bioanalytical Systems, West Lafayette, IN) software.
Excel 3D Format
This option applies only to SECM image data (CHI 900 series). When this box is checked, the output
text data file can be read directly by Excel (© Microsoft Corp., Redmond, WA) to generate a 3D surface
plot.
To generate Excel 3D surface plots, follow these instructions:
1.
2.
3.
4.
Start the Excel Program.
Open the target text data file created by the CHI900/CHI900A/CHI900B program.
The "Text Import Wizard - Step 1 of 3" dialog box will appear. Click "Next".
The "Text Import Wizard - Step 2 of 3" dialog box will appear. Change the Delimiters setting to match
the data separator used in the output text file. Click "Finish". A spreadsheet containing the data will
appear.
5. Select all data points in the spreadsheet.
6. Click the "Chart" command in the "Insert" menu.
7. The "ChartWizard - Step 1 of 4" dialog box will appear. Choose "Surface" and click "Next".
8. The "ChartWizard - Step 2 of 4" dialog box will appear. Choose "Rows" and click "Next".
9. The "ChartWizard - Step 3 of 4" dialog box will appear. Enter descriptive labels and change graph
options as desired. Click "Finish" when done.
10. A 3D surface plot will appear in the spreadsheet data area. You can resize the plot by left-clicking
© 2014 CH Instruments, Inc.
File Menu
41
and dragging on the edges of the plot.
11. Copy and paste the graph into a word processor for further usage or printing. Exporting the graph to a
picture format like JPEG or PNG (e.g., by pasting in Paint) and inserting the resulting picture into a
word processor document will generally reduces the final file’s size, but will also lower the resolution
of the plot.
If the data density is so high that the lines between data points cannot be seen clearly, set the data
point interval to more than 1 as described above.
Nanoscope Header
This option applies only to SECM image data (CHI 900 series). When this box is checked, the output
text data file will be directly readable by Nanoscope (© Veeco Instruments Inc., Santa Barbara, CA)
software to create a 3D image. However, as Veeco Instruments frequently updates their Nanoscope
software, your generated text file may not be readable if your version of Nanoscope is older than the CHI
900B series software.
© 2014 CH Instruments, Inc.
42
3.9
CH Instruments Model 900D Series
Import Text File command
This deprecated command opens the Import Text File dialog box.
Use the Import Text File command to import text files; CHI and BAS text file formats are both
supported.
For CHI text files, this command will only succeed if Memo and Parameter fields are present.
For BAS text files, parameters will be converted to be CHI format.
This command can only import one text file at a time; to import multiple files, use the Open command
instead.
The Import Text File command presents this dialog box.
© 2014 CH Instruments, Inc.
File Menu
3.10
43
Print command
Use this command to print a document.
The printer output is identical to what is displayed on the screen (What You See Is What You Get). Use
the Graph Option command in the Graphics menu to customize the print output.
The paper orientation must be set to landscape. If a warning pops up, use the Print Setup command to
set the paper orientation to landscape.
This command has a toolbar button:
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3.11
CH Instruments Model 900D Series
Print Multiple Files command
This command opens the Multiple File Print dialog box. Printer output is identical to what is displayed on
the screen (What You See Is What You Get). Use the Graph Option command under the Graphics
menu to customize the print output.
Use this command to print multiple data files.
The Print Multiple Files command presents this dialog box.
The following options allow you to specify the name and location of the binary data files you're about to
print:
File name
Type or select the filename(s) you want to print. The box above lists files with the extension you select
in the "Files of type" box. To select multiple files, hold down the Ctrl key and left-click on the desired
files.
You don't have to type the extension, the system will automatically attach a ".bin" extension to the
filename. Other extensions are not allowed.
Files of type
Select the type of file you want to print. Only ".bin" files (binary data) are available.
© 2014 CH Instruments, Inc.
File Menu
3.12
45
Print Setup command
This command opens the Print Setup dialog box. Use this command to select a printer and a printer
connection. This command presents a Print Setup dialog box, where you specify the printer and its
connection.
Printer Name
Specifies the printer you want to use. Use the default printer, or select one of the currently installed
printers shown in the box. You can install printers and configure ports using the Windows Control Panel.
Printer Properties
Displays a dialog box where you can make additional choices about printing, specific to the type of
printer you have selected.
Orientation
Specifies Portrait or Landscape. The paper orientation should be set to landscape in the CHI program
environment. If you choose Portrait and try to print, a warning may pop up, and you will have to use the
Print Setup command to set the paper orientation back to landscape.
Paper Size
Specifies the size of paper that the document is to be printed on.
Paper Source
Specifies the paper source, because some printers offer multiple trays for different paper sources.
Network
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46
CH Instruments Model 900D Series
Click this button to connect to a network location, assigning it a new drive letter.
© 2014 CH Instruments, Inc.
File Menu
3.13
47
Exit command
Use this command to end your program session. The program prompts you to save documents with
unsaved changes. Upon exiting, settings including directory, system setup, control status, macros, data
processing, simulation, and graphics options, color, and font will be saved.
© 2014 CH Instruments, Inc.
Setup Menu
Chapter 4
Setup Menu
The Setup menu offers the following commands:
Technique
Parameters
System
Hardware Test
© 2014 CH Instruments, Inc.
Select one of many electrochemical techniques.
Choose experimental parameters.
Set system defaults.
Test system hardware.
49
50
4.1
CH Instruments Model 900D Series
Technique command
This command opens the Electrochemical Techniques dialog box.
Use this command to select an electrochemical technique. This frequently used command is the
fountainhead from whence all experiments spring forth.
This command has a toolbar button:
The Technique command presents this dialog box, which lists all electrochemical techniques available
on your instrument.
Technique Selection
There are multiple ways to perform technique selection:
Double-click the desired technique
Single-click the technique, then click OK
Single-click the technique, then press Enter
Use the Up/Down arrow keys, then press Enter.
Tech Help
Click this button to toggle technique-specific help. When this is enabled, information about the selected
technique will be displayed automatically. Tech Help is not compatible with the Old Help option. Also,
please note that the parameter value ranges and technical details shown here may not apply to your
instrument model; for model-specific information, click Help once a technique-specific dialog box is
shown.
Show on startup
When this option is checked, this dialog box will be presented each time the program starts.
Show for new documents
When this option is checked, this dialog box will be presented each time you create a new document.
Use current tech on startup
When this option is checked, the currently selected technique will become the new default when the
program starts, as well as for all new documents. This will not take effect if you click Cancel or the close
button.
Always confirm parameters
When this option is checked, a parameters dialog box will always be displayed after technique
selection, even if your selection has not changed.
Run prompt after params
When this option is checked, you will be asked whether to run the experiment immediately after
confirming parameter values.
© 2014 CH Instruments, Inc.
Setup Menu
51
Polarographic Mode
When this option is checked, polarographic mode will be enabled, allowing the mercury drop to grow and
be dislodged for every data point.
Polarographic mode is available only for the following techniques:
Differential Pulse Polarography (DPP)
Normal Pulse Polarography (NPP)
Enabling polarographic mode will automatically disable stripping mode. To re-enable stripping mode, the
Polarographic Mode option must be unchecked.
View as tree
When this option is checked, the Technique Selection item will be displayed as a categorized list. The
categories can be expanded or collapsed by clicking the plus or minus boxes to their left. The program
will remember which categories you previously had expanded.
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4.2
CH Instruments Model 900D Series
Parameters command
This command opens a dialog box to set experimental parameters for the technique currently selected in
the Electrochemical Techniques dialog box.
This command has a toolbar button:
The following parameter dialog boxes available for your instrument series are listed below. For details
about each technique, please refer to the description of each dialog box.
Parameters
Parameters
Parameters
Parameters
Parameters
Parameters
Parameters
Parameters
Parameters
Parameters
Parameters
Parameters
Parameters
Parameters
Parameters
Parameters
Parameters
Parameters
Parameters
Parameters
Parameters
Parameters
Parameters
Parameters
Parameters
Parameters
Parameters
Parameters
Parameters
Parameters
Parameters
Parameters
Parameters
Parameters
Parameters
Parameters
Parameters
Parameters
for Cyclic Voltammetry
for Linear Sweep Voltammetry
for Staircase Voltammetry
for Tafel Plot
for Chronoamperometry
for Chronocoulometry
for Differential Pulse Voltammetry
for Normal Pulse Voltammetry
for Differential Normal Pulse Voltammetry
for Square Wave Voltammetry
for A.C. Voltammetry
for 2nd Harmonic A.C. Voltammetry
for FT A.C. Voltammetry
for Amperometric i-t Curve
for Differential Pulse Amperometry
for Double Differential Pulse Amperometry
for Triple Pulse Amperometry
for Integrated Pulse Amperometric Detection
for Bulk Electrolysis with Coulometry
for Hydrodynamic Modulation Voltammetry
for Sweep-Step Functions
for Multi-Potential Steps
for A.C. Impedance
for Impedance - Time
for Impedance - Potential
for Chronopotentiometry
for Chronopotentiometry with Current Ramp
for Multi-Current Steps
for Potentiometric Stripping Analysis
for Electrochemical Noise Measurement
for Open Circuit Potential - Time
for Surface Patterned Conditioning
for Probe Scan Curve
for Probe Approach Curve
for Surface Interrogation SECM
for Scanning Electrochemical Microscope
for Z Probe Constant Current Control
for Sampling Scheme
© 2014 CH Instruments, Inc.
Setup Menu
4.2.1
53
Cyclic Voltammetry Parameters dialog box
In Cyclic Voltammetry (CV), the potential is linearly swept from Init E to High E (or Low E, depending on
the Init P/N polarity parameter). The potential is then swept back in the reverse direction. The following
diagram shows the applied potential waveform as a function of time. Current is recorded as a function of
potential.
Potential(V)
High E
Scan Rate (V/s)
Init E
Low E
Segment 1
Segment 2
Segment 3
Time (s)
Parameter
Init E (V)
High E (V)
Low E (V)
Final E (V)
Init P/N
Scan Rate (V/s)
Sweep Segments
Sample Int. (V)
Quiet Time (sec)
Sensitivity (A/V)
Auto Sens
Enable Final E
Aux. Signal Rec.
Range
-10 - +10
-10 - +10
-10 - +10
-10 - +10
Pos. or Neg.
1e-6 - 10000
1 - 1000000
0.001 - 0.064
0 - 100000
1e-12 - 0.1
Check or Uncheck
Check or Uncheck
Check or Uncheck
Description
Initial potential
Upper limit of potential scan
Lower limit of potential scan
Final potential (if enabled)
Initial scan direction
Potential scan rate
Sweep segments (each is half cycle)
Data sampling interval
Quiescent time before potential scan
Sensitivity scale
Automatic sensitivity switching during run
Allow potential scan to end at Final E
Record external signal
Electrode 2:
Potential (V)
Differential E (V)
Sensitivity (A/V)
Off
Constant E
Scan
Diff Scan
-10 - +10
-0.2 - +0.2
1e-12 - 0.1
Select or deselect
Select or deselect
Select or deselect
Select or deselect
Second working electrode potential
Potential difference with 1st channel if Diff Scan is enabled
Sensitivity scale for second electrode
Second working electrode turned off
Hold second electrode at constant potential
Scan 2nd channel with 1st channel
Scan 2nd channel at constant potential difference with 1st
channel
Notes
© 2014 CH Instruments, Inc.
54
CH Instruments Model 900D Series
The potential increment is 0.1 mV when the scan rate is below 1000 V/s, 1 mV at 5000 V/s, and 2 mV
at 10000 V/s.
High E and Low E should be at least 0.01 V apart.
If unreasonably values for High E or Low E are entered, the system will automatically readjust them.
Depending on the Init E, High E, and Low E values, the system will automatically readjust the initial
scan direction.
The maximum potential scan range is 13.1V.
The sampling interval can be 1 mV when the scan rate is below 1000 V/s, 2 mV below 2000 V/s, 5
mV below 5000 V/s, and 10 mV below 10000 V/s. The data sampling interval will be automatically
increased at high scan rates.
When a large number of sweep segments is involved, the data sampling interval will be automatically
increased up to 0.02 V. If the scan rate is higher than 0.5 V/s (or 3 V/s using fast com port speed),
the number of sweep segments will be limited by the instrument memory size (64K points). If the scan
rate is lower than 0.5 V/s (or 3 V/s using fast com port speed), the maximum data length specified by
the System command will take effect. When the scan rate is low, the specified sweep segments will
be executed, but only a limited number of segments will be stored. Large sweep segments can be
useful for, say, electrode conditioning.
When the scan rate is below 0.01 V/s, the sensitivity scale during the run can be automatically
adjusted according to the current level. When Auto Sens is enabled, the value of the Sensitivity field
will have no effect on the measurement. However, the smallest available automatic sensitivity will be
1e-6 A/V instead of 1e-12 A/V. The Picoamp Booster will not work either. In order to specify smaller
sensitivities, the automatic sensitivity switching option must be disabled.
The Enable Final E option will allow you to scan complete cycles when the number of Sweep
Segments is odd and Initial E is different from High E and Low E. Check the Enable Final E box and
set Final E equal to Initial E, and the last segment will stop at Initial E instead of High E or Low E.
It is possible to record external voltage signals (e.g., spectroscopic signals) simultaneously with the
voltammogram (maximum scan rate may be limited). Use the 9-pin D-connector on the rear panel for
signal input. Consult the User's Manual for the pin-out and signal level requirements.
When the second electrode is in Scan mode, it will have the same potential as the primary electrode
throughout the experiment. The potential of the second electrode is therefore not independent.
When the second electrode is enabled, the maximum scan rate is reduced to 100 V/s and the
sampling interval will be doubled at high scan rates.
When the second electrode is enabled, the auxiliary signal recording channel will be disabled.
© 2014 CH Instruments, Inc.
Setup Menu
4.2.2
55
Linear Sweep Voltammetry Parameters dialog box
In Linear Sweep Voltammetry (LSV), the potential is scanned from Init E toward Final E. The following
diagram shows the potential waveform applied as a function of time. Current is recorded as a function of
potential.
Potential(V)
Final E
Scan Rate (V/s)
Init E
Time (s)
Parameter
Init E (V)
Final E (V)
Scan Rate (V/s)
Sample Int. (V)
Quiet Time (sec)
Sensitivity (A/V)
Auto Sens
Aux. Signal Rec.
Range
-10 - +10
-10 - +10
1e-6 - 20000
0.001 - 0.064
0 - 100000
1e-12 - 0.1
Check or Uncheck
Check or Uncheck
Description
Initial potential
Final potential
Potential scan rate
Data sampling interval
Quiescent time before potential scan
Sensitivity scale
Automatic sensitivity switching during run
Record external signal when scan rate < 0.1 V/s
Electrode 2:
Potential (V)
Differential E (V)
Sensitivity (A/V)
Off
Constant E
Scan
Diff Scan
-10 - +10
-0.2 - +0.2
1e-12 - 0.1
Select or deselect
Select or deselect
Select or deselect
Select or deselect
Second working electrode potential
Potential difference with 1st channel if Diff Scan is enabled
Sensitivity scale for second electrode
Second working electrode turned off
Hold second electrode at constant potential
Scan 2nd channel with 1st channel
Scan 2nd channel at constant potential difference with 1st
channel
Notes
Init E and Final E should be at least 0.01 V apart.
The maximum potential scan range is 13.1 V.
When the scan rate is high, the data sampling interval will be automatically increased.
When the scan rate is below 0.01 V/s, the sensitivity scale during the run can be automatically
adjusted according to the current level. When Auto Sens is enabled, the value of the Sensitivity field
will have no effect on the measurement. However, the smallest available automatic sensitivity will be
© 2014 CH Instruments, Inc.
56
CH Instruments Model 900D Series
1e-6 A/V instead of 1e-12 A/V. The Picoamp Booster will not work either. In order to specify smaller
sensitivities, the automatic sensitivity switching option must be disabled.
Linear polarization resistance plots can be generated using the Special Plots command under the
Graphics menu.
The potential increment is 0.1 mV when the scan rate is below 1000 V/s, 1 mV at 5000 V/s, and 4 mV
at 20000 V/s.
The sampling interval can be 1 mV when the scan rate is below 1000 V/s, 2 mV at 2000 V/s, 5 mV at
5000 V/s, and 20 mV at 20000 V/s. The data sampling interval will be automatically increased at high
scan rates.
If the scan rate is below 0.1 V/s, it is possible to record external voltage signals (e.g., spectroscopic
signals) simultaneously with the voltammogram. The input full scale range is +/-10V. Use the 9-pin Dconnector on the real panel for signal input. Consult the User Manual for the pin-out and signal level
requirements.
When the second electrode is enabled, the auxiliary signal recording channel will be disabled.
When the second electrode is in Scan mode, it will have the same potential as the primary electrode
throughout the experiment. The potential of the second electrode is therefore not independent.
When the second electrode is enabled, the maximum scan rate is reduced to 100 V/s and the
sampling interval will be doubled at high scan rates.
© 2014 CH Instruments, Inc.
Setup Menu
4.2.3
57
Staircase Voltammetry Parameters dialog box
In Staircase Voltammetry (SCV), the potential is incremented from Init E toward Final E, and it may be
scanned back. The following diagram shows the potential waveform applied as a function of time. Current
is sampled after every potential increment and recorded as a function of potential.
Potential(V)
Final E
Incr E
Sample Width
Init E
Segment 1
Step Period
Segment 2
Time (s)
Parameter
Range
Init E (V)
-10 - +10
Final E (V)
-10 - +10
Incr E (V)
1e-3 - 0.05
Segments
1 - 1000
Sampling Width (s)1e-4 - 50
Step Period (s)
0.001 - 50
Quiet Time (sec) 0 - 100000
Sensitivity (A/V)
1e-12 - 0.1
Description
Initial potential
Final potential
Increment potential of each step
Number of scan segments
Data sampling width for each point
Potential step period or dropping time
Quiescent time before potential scan
Sensitivity scale
Electrode 2:
Potential (V)
Sensitivity (A/V)
On
Scan
Second working electrode potential (if not scan)
Sensitivity scale for second electrode
Second electrode at constant potential
Scan the second electrode potential
-10 1e-12
Check
Check
+10
- 0.1
or Uncheck
or Uncheck
Notes
Init E and Final E should be at least 0.01 V apart.
Sampling Width should be no more than half of Step Period; otherwise the system will automatically
readjust the former.
Data sampling always occurs at the end of each step.
When the second electrode is in Scan mode, it will have the same potential as the primary electrode
throughout the experiment. The potential of the second electrode is therefore not independent.
© 2014 CH Instruments, Inc.
4.2.4
CH Instruments Model 900D Series
Tafel Plot Parameters dialog box
In the Tafel Plot technique (TAFEL), the potential is scanned from Init E toward Final E. The potential
may be held there and then scanned back. The following diagram shows the potential waveform applied
as a function of time. The logarithm of current is recorded as a function of potential.
Final E
Potential(V)
58
Hold Time
Scan Rate (V/s)
Init E
Segment 1
Segment 2
Time (s)
Parameter
Init E (V)
Final E (V)
Incr E (V)
Sweep Segments
Scan Rate (V/s)
Quiet Time (sec)
Sensitivity (A/V)
Auto Sens
Range
-10 - +10
-10 - +10
1e-3 - 0.05
1 - 2
1e-6 - 0.01
0 - 100000
1e-12 - 0.1
Check or Uncheck
Description
Initial potential
Final potential
Increment potential of each step
Sweep segments; each segment is half cycle
Potential scan rate
Quiescent time before potential scan
Sensitivity scale
Automatic sensitivity switching during run
Notes
Init E and Final E should be at least 0.01 V apart.
Corrosion rate calculations can be performed using the Special Analysis command under the Analysis
menu.
© 2014 CH Instruments, Inc.
Setup Menu
4.2.5
59
Chronoamperometry Parameters dialog box
In Chronoamperometry (CA), the potential is stepped from Init E to either High E or Low E depending on
the Init P/N and may then be stepped back. The following diagram shows the potential waveform applied
as a function of time. Current is recorded as a function of time.
Potential(V)
High E
Pulse Width
High E
Pulse Width
Init E
Low E
Step 1
0
Step 2
Step 3
Time (s)
Parameter
Range
Init E (V)
-10 - +10
High E (V)
-10 - +10
Low E (V)
-10 - +10
Init P/N
Pos. or Neg.
Number of Steps 1 - 320
Pulse Width (s)
1e-4 - 1000
Sample Interval (s) 1e-6 - 10
Quiet Time (s)
0 - 100000
Sensitivity (A/V)
1e-12 - 0.1
Aux. Signal Rec. Check or Uncheck
Description
Initial potential
Upper limit of potential step
Lower limit of potential step
Initial step direction
Number of potential steps
Potential pulse width
Data sampling interval
Quiescent time before potential step
Sensitivity scale
Record external signal when sample interval >= 0.005s
Electrode 2:
Potential (V)
Sensitivity (A/V)
On
Step
Second working electrode potential if not step
Sensitivity scale for second electrode
Second working electrode at constant E
Step the second electrode potential
-10 1e-12
Check
Check
+10
- 0.1
or Uncheck
or Uncheck
Notes
High E and Low E should be at least 0.001 V apart.
If unreasonably values for High E or Low E are entered, the system will automatically readjust them.
Depending on the Init E, High E, and Low E values, the system will automatically readjust the initial
scan direction.
The maximum potential scan range is 13.1V.
A shorter sampling interval will increase data density but also reduce the signal-noise ratio. If earlier
transient data points are important, a shorter sampling interval is recommended. If later data points are
of interest, a longer sampling interval is recommended. However, a minimum of 100 points per step is
© 2014 CH Instruments, Inc.
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CH Instruments Model 900D Series
required.
If the sampling interval is shorter than 0.002s (or 0.0005s with fast com port speed), data will not be
transferred in real time, but rather after the experiment is completed. The cell is turned off during data
transfer unless the Cell On between Run option has been enabled using the Cell command. The total
number of data points will be limited by the instrument memory size (64K points). The sampling
interval may be automatically adjusted to fit the data points in a reasonable range.
If the sampling interval is longer than 0.002s (or 0.0005s with fast com port speed), data will be
transferred in real time during the experiment. The number of data points for each step will be limited
by the instrument memory size (64K points). The sampling interval may be automatically adjusted to
fit the data points in a reasonable range.
If the sampling interval is greater than 0.005s, it is possible to record external voltage signals (e.g.,
spectroscopic signals) simultaneously with the voltammogram. Use the 9-pin D-connector on the rear
panel for signal input. Consult the User's Manual for the pin-out and signal level requirements.
When the second electrode is set to Step, its potential will be the same as the primary electrode; it is
not independent.
© 2014 CH Instruments, Inc.
Setup Menu
4.2.6
61
Chronocoulometry Parameters dialog box
In Chronocoulometry (CC), the potential is stepped from Init E to Final E and may then be stepped back.
The following diagram shows the potential waveform applied as a function of time. The charge passing
through the working electrode is recorded as a function of time.
Potential(V)
Final E
Pulse Width
Final E
Pulse Width
Init E
Init E
Step 1
Step 2
Step 3
0
Parameter
Range
Init E (V)
-10 - +10
Final E (V)
-10 - +10
Number of Steps 1 - 320
Pulse Width (s)
1e-4 - 1000
Sample Interval (s) 1e-6 - 10
Quiet Time (s)
0 - 100000
Sensitivity (A/V)
1e-12 - 0.1 or
1e-9 - 1e-6 C/V
Time (s)
Description
Initial potential
Final potential
Number of potential steps
Potential pulse width
Data sampling interval
Quiescent time before potential step
Sensitivity scale
Notes
Init E and Final E should be at least 0.01 V apart.
The maximum potential step range is 13.1 V.
A true integrator (charge-to-voltage converter) can be employed, in which case the sensitivity is 1e-9 to
1e-6 C/V. If charge exceeds 8e-6 coulombs, the capacitor of the integrator will be discharged and the
new charge will be added to the previous value. This allows higher charge to be measured with the
integrator. There may be discontinuities in the charge-time curve due to this capacitor discharge.
These discontinuities should be negligible, but if they turn out to have a significant effect on the
measurement, you can use the current-to-voltage converter instead and use the software integrator to
convert current to charge.
A current-to-voltage converter is not ideal for chronocoulometry, particularly if early transient data are
important as in double layer capacitance or surface reactions. A charge-to-voltage converter (true
integrator) is a better choice.
If the current-to-voltage converter is employed due to high total charge, a shorter sampling interval will
increase data density but also reduce the signal-to-noise ratio. If earlier transient data are important, a
shorter sampling interval is recommended. If later data points are of interest, a longer sampling interval
is recommended. However, a minimum of 1000 points per step is required unless the sampling rate
© 2014 CH Instruments, Inc.
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CH Instruments Model 900D Series
does not allow it.
If the sampling interval is shorter than 0.002s (or 0.0005s with fast com port speed), data will not be
transferred in real time, but rather after the experiment is completed. The cell is turned off during data
transfer unless the Cell On between Run option has been enabled using the Cell command. The total
number of data points will be limited by the instrument memory size (64K points). The sampling
interval may be automatically adjusted to fit the data points in a reasonable range.
If the sampling interval is longer than 0.002s (or 0.0005s with fast com port speed), data will be
transferred in real time during the experiment. The number of data points for each step will be limited
by the instrument memory size (64K points). The sampling interval may be automatically adjusted to
fit the data points in a reasonable range.
If the current-to-voltage converter is employed, during the run, an “Overflow” warning may appear. This
is caused by the current transient immediately following the potential step. If the intercept (which gives
information about double layer capacitance and adsorption) of the Anson plot (Q-t^1/2 plot) is not your
primary interest, you need not worry about this. However, if data distortion can be observed visually,
you should lower the sensitivity scale.
In some cases, you may want to use the i/E converter filter to slow the system down, but make sure
that the time constant of the filter (1/cutoff freq) is much shorter than the pulse width.
In order to reduce noise and enhance measurement accuracy, it is recommended to use the highest
sensitivity scale possible.
© 2014 CH Instruments, Inc.
Setup Menu
4.2.7
63
Differential Pulse Voltammetry Parameters dialog box
Potential(V)
In Differential Pulse Voltammetry (DPV), the base potential is incremented from Init E toward Final E. A
potential pulse is applied. Current is sampled before the potential pulse and at the end of the pulse. The
difference between these two current samples is recorded as a function of potential. The following
diagram shows the potential waveform applied as a function of time and the current sampling scheme.
Pulse Width
Amplitude
Final E
Incr E
Init E
Pulse Period
Sample Width
Time (s)
Parameter
Init E (V)
Final E (V)
Incr E (V)
Amplitude (V)
Pulse Width (s)
Sample Width (s)
Pulse Period (s)
Quiet Time (s)
Sensitivity (A/V)
Range
-10 - +10
-10 - +10
0.001 - 0.05
±0.001 - ±0.5
1e-3 - 10
1e-4 - 10
0.01 - 50
0 - 100000
1e-12 - 0.1
Description
Initial potential
Final potential
Increment potential of each pulse
Potential pulse amplitude
Potential pulse width
Data sampling width
Potential pulse period or dropping time
Quiescent time before potential pulses begin
Sensitivity scale
Electrode 2:
Potential (V)
Sensitivity (A/V)
On
Scan
-10 1e-12
Check
Check
Second working electrode potential if not step
Sensitivity scale for second electrode
Second working electrode at constant E
Scan the second electrode potential
+10
- 0.1
or Uncheck
or Uncheck
Notes
Init E and Final E should be at least 0.01 V apart.
Pulse Width should be no more than half of Pulse Period; otherwise the system will automatically
readjust Pulse Width.
Sample Width should be no more than half of Pulse Width; otherwise the system will automatically
readjust Sample Width.
When Amplitude is negative, the pulse direction will in the opposite direction of the potential scan.
When the second electrode is set to Scan, its potential will be the same as the primary electrode; it is
not independent.
© 2014 CH Instruments, Inc.
4.2.8
CH Instruments Model 900D Series
Normal Pulse Voltammetry Parameters dialog box
In Normal Pulse Voltammetry (NPV), the base potential is held at Init E, and a sequence of potential
pulses with increasing amplitude is applied. The current at the end of each potential pulse is sampled
and recorded as a function of the pulse potential. The following diagram shows the potential waveform
applied as a function of time and the current sampling scheme.
Potential(V)
64
Pulse Width
Final E
Incr E
Init E
Pulse Period
Sample Width
Time (s)
Parameter
Range
Init E (V)
-10 - +10
Final E (V)
-10 - +10
Incr E (V)
0.001 - 0.05
Pulse Width (s)
1e-3 - 10
Sampling Width (s)1e-4 - 10
Pulse Period (s)
0.01 - 50
Quiet Time (s)
0 - 100000
Sensitivity (A/V)
1e-12 - 0.1
Description
Initial potential
Final potential
Increment potential of each pulse
Potential pulse width
Data sampling width
Potential pulse period or dropping time
Quiescent time before potential pulses begin
Sensitivity scale
Electrode 2:
Potential (V)
Sensitivity (A/V)
On
Scan
Second working electrode potential if not scan
Sensitivity scale for second electrode
Second working electrode at constant E
Scan the second electrode potential
-10 1e-12
Check
Check
+10
- 0.1
or Uncheck
or Uncheck
Notes
Init E and Final E should be at least 0.01 V apart.
Pulse Width should be no more than half of Pulse Period; otherwise the system will automatically
readjust Pulse Width.
Sample Width should be no more than half of Pulse Width; otherwise the system will automatically
readjust Sample Width.
When the second electrode is set to Scan, its potential will be the same as the primary electrode; it is
not independent.
© 2014 CH Instruments, Inc.
Setup Menu
4.2.9
65
Differential Normal Pulse Voltammetry dialog box
Potential(V)
In Differential Normal Pulse Voltammetry (DNPV), the base potential is held at Init E, and a sequence of
dual potential pulses is applied. The magnitude of the first pulse increments after every iteration, and the
second pulse has a constant amplitude relative to the first. Current is sampled at the end of both
potential pulses, and the difference of these two values is recorded as a function of the first pulse
potential. The following diagram shows the potential waveform applied as a function of time and the
current sampling scheme.
Pulse Width
Incr E
Pulse Width
Final E
Amplitude
Init E
Pulse Period
Sample Width
Time (s)
Parameter
Range
Init E (V)
-10 - +10
Final E (V)
-10 - +10
Incr E (V)
0.001 - 0.05
Amplitude (V)
0.001 - 0.5
1st Pulse Width (s) 0.001 - 0.02
2nd Pulse Width 0.001 - 0.02
Sampling Width (s)0.001 - 0.5
Pulse Period (s)
0.05 - 50
Quiet Time (s)
0 - 100000
Sensitivity (A/V)
1e-12 - 0.1
Open Circuit
Check or Uncheck
Description
Initial potential
Final potential
Increment potential of each pulse
Potential pulse amplitude
First potential pulse width
Second potential pulse width
Data sampling width
Potential pulse period or dropping time
Quiescent time before potential pulses begin
Sensitivity scale
Hold Step 1 at open circuit or constant potential
Notes
Init E and Final E should be at least 0.01 V apart.
Pulse Width should be no more than half of Pulse Period; otherwise the system will automatically
readjust Pulse Width.
Sample Width should be no more than half of Pulse Width; otherwise the system will automatically
readjust Sample Width.
In Differential Normal Pulse Voltammetry, consists of three steps (constant potential levels) per cycle.
The potential of the first step is normally held at Initial E, where no electrochemical reaction will occur.
The second step and third steps are incremented by Incr E every cycle, with the third step always
more positive (negative) for a positive (negative) scan than the second potential by Amplitude. Current
samples are taken every cycle at the end of the second and third steps, and the difference between
the two current samples is reported as a function of the second potential.
© 2014 CH Instruments, Inc.
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CH Instruments Model 900D Series
4.2.10 Square Wave Voltammetry Parameters dialog box
Potential(V)
In Square Wave Voltammetry (SWV), the base potential is incremented from Init E towards Final E. A
square wave potential is superimposed onto the base potential, which increments after each cycle of the
square wave. Current is sampled at the end of the forward and reverse steps and recorded as a function
of the base potential. During the experiment, only the difference between the two current samples is
displayed. After the experiment, the forward and reverse currents will also be available for display. The
following diagram shows the potential waveform applied as a function of time and the current sampling
scheme.
Incr E
Final E
Amplitude
Init E
1/Frequency
Sample Width
Time (s)
Parameter
Init E (V)
Final E (V)
Incr E (V)
Amplitude (V)
Frequency (Hz)
Quiet Time (s)
Sensitivity (A/V)
Range
-10 - +10
-10 - +10
0.001 - 0.05
0.001 - 0.5
1 - 100000
0 - 100000
1e-12 - 0.1
Description
Initial potential
Final potential
Increment potential of each pulse
Square wave amplitude
Square wave frequency
Quiescent time before potential pulses begin
Sensitivity scale
Electrode 2:
Potential (V)
Sensitivity (A/V)
On
Scan
-10 1e-12
Check
Check
Second working electrode potential if not scan
Sensitivity scale for second electrode
Second working electrode at constant E
Scan the second electrode potential
+10
- 0.1
or Uncheck
or Uncheck
Notes
Init E and Final E should be at least 0.01 V apart.
Forward, reverse, and difference currents are recorded. Use the Graph Option command under the
Graphics menu to specify data display options.
When the second electrode is set to Scan, its potential will be the same as the primary electrode; it is
not independent.
© 2014 CH Instruments, Inc.
Setup Menu
67
4.2.11 AC Voltammetry Parameters dialog box
Potential(V)
In [Second Harmonic] AC Voltammetry ([SH]ACV), the base potential is incremented from Init E toward
Final E, and a sequential sine waveform is superimposed. Current is sampled when the AC signal is
applied, and it[s second harmonic component] is analyzed using a software lock-in amplifier. During the
experiment, only the absolute [second harmonic] AC current is displayed. After the experiment, the
phase-selective [second harmonic] current at any phase angle will also be available for display. The
following diagram shows the potential waveform applied as a function of time.
Incr E
Final E
Amplitude
Init E
Sample Period
Time (s)
Parameter
Init E (V)
Final E (V)
Incr E (V)
Amplitude (V)
Frequency (Hz)
Sample Period (s)
Quiet Time (s)
Sensitivity (A/V)
Bias DC Current
Auto Sens
Range
-10 - +10
-10 - +10
0.001 - 0.05
0.001 - 0.5
0.1 - 10000
0.1 - 50
0 - 100000
1e-12 - 0.1
off - range - on
Check or Uncheck
Description
Initial potential
Final potential
Increment potential of each pulse
AC amplitude
AC frequency
Data sampling period or dropping time
Quiescent time before potential pulses begin
Sensitivity scale
Enable DC current bias during run
Automatic sensitivity switching during run
Notes
Init E and Final E should be at least 0.01 V apart.
Depending on the frequency range, it may not be possible to generate the requested AC frequency; in
this case, the closest available frequency will be applied.
When the AC frequency is 2 Hz or lower, the Sample Period parameter should be at least 2 seconds;
if not, the system will automatically readjust the Sample Period.
Both absolute current and phase-selective current are available. Use the Graph Option command
under the Graphics menu to specify data display options.
When DC current is high and AC current is low, sensitivity cannot be increased because the DC
current will overflow. This problem is more serious when the frequency is relatively low. The application
of a DC current bias allows higher AC signal amplification. A 16-bit DAC is used for this purpose. On
the other hand, if the DC current is not expected to be large and the frequency is high, a DC current
bias may be unnecessary.
© 2014 CH Instruments, Inc.
68
CH Instruments Model 900D Series
4.2.12 2nd Harmonic AC Voltammetry Parameters dialog box
Potential(V)
In [Second Harmonic] AC Voltammetry ([SH]ACV), the base potential is incremented from Init E toward
Final E, and a sequential sine waveform is superimposed. Current is sampled when the AC signal is
applied, and it[s second harmonic component] is analyzed using a software lock-in amplifier. During the
experiment, only the absolute [second harmonic] AC current is displayed. After the experiment, the
phase-selective [second harmonic] current at any phase angle will also be available for display. The
following diagram shows the potential waveform applied as a function of time.
Incr E
Final E
Amplitude
Init E
Sample Period
Time (s)
Parameter
Init E (V)
Final E (V)
Incr E (V)
Amplitude (V)
Frequency (Hz)
Sample Period (s)
Quiet Time (s)
Sensitivity (A/V)
Bias DC Current
Auto Sens
Range
-10 - +10
-10 - +10
0.001 - 0.05
0.001 - 0.5
0.1 - 5000
0.1 - 50
0 - 100000
1e-12 - 0.1
off - range - on
Check or Uncheck
Description
Initial potential
Final potential
Increment potential of each pulse
AC amplitude
AC frequency
Data sampling period or dropping time
Quiescent time before potential pulses begin
Sensitivity scale
Enable DC current bias during run
Automatic sensitivity switching during run
Notes
Init E and Final E should be at least 0.01 V apart.
Depending on the frequency range, it may not be possible to generate the requested AC frequency; in
this case, the closest available frequency will be applied.
When the AC frequency is 2 Hz or lower, the Sample Period parameter should be at least 2 seconds;
if not, the system will automatically readjust the Sample Period.
Both absolute current and phase-selective current are available. Use the Graph Option command
under the Graphics menu to specify data display options.
When DC current is high and AC current is low, sensitivity cannot be increased because the DC
current will overflow. This problem is more serious when the frequency is relatively low. The application
of a DC current bias allows higher AC signal amplification. A 16-bit DAC is used for this purpose. On
the other hand, if the DC current is not expected to be large and the frequency is high, a DC current
bias may be unnecessary.
© 2014 CH Instruments, Inc.
Setup Menu
69
4.2.13 FT AC Voltammetry Parameters dialog box
In Fourier Transform AC Voltammetry (FTACV), the DC potential is scanned from Init E to Final E in
increments of 0.3 mV. On top of this DC scan, a sine waveform is superimposed, applied continuously
without interruption. The resulting current is sampled and displayed directly at all times (cf. ACV). Once
the experiment is complete, data analysis by Fourier transform yields the absolute AC current, DC
current, first, second, third, and fourth harmonic components, as well as the complete response
spectrum. Hence, a very rich set of information can be obtained from a single measurement.
Parameter
Init E (V)
Final E (V)
Frequency (Hz)
Amplitude (V)
Total Data Point
Data Points Per
Sine
Sweep Segments
Quiet Time (s)
Sensitivity (A/V)
Range
-10 - +10
-10 - +10
0.1 - 50
0.001 - 0.5
8192 - 65536
4 - 256
Description
Initial potential
Final potential
AC frequency
AC amplitude
Total number of data points sampled
Number of data points per AC waveform period
1 - 2
0 - 100000
1e-12 - 0.1
Single or cyclic DC potential scan
Quiescent time before potential scan
Sensitivity scale
Notes
Init E and Final E should be at least 0.01 V apart.
For a given frequency, the more data points per sine wave, the faster the sampling rate will be. Faster
sampling will result in less noise (more signal averaging), but lower data density. If the specified
sampling rate exceeds 3 KHz, data will be be displayed at the end of the experiment instead of in real
time.
The total measurement time in seconds is equal to the total number of points / points per sine wave /
frequency.
The potential scan rate in turn is equal to the specified potential range divided by the total
measurement time.
The absolute AC current, DC current, first, second, third, and fourth harmonic components, and the
complete response spectrum can be plotted using the Graph Option command under the Graphics
menu.
© 2014 CH Instruments, Inc.
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CH Instruments Model 900D Series
4.2.14 Amperometric i-t Curve dialog box
Potential(V)
In the Amperometric i-t Curve technique (i-t), a constant potential is applied, and current is recorded as a
function of time. The following diagram shows the potential waveform applied as a function of time and
the current sampling scheme.
Sample Interval
Init E
0
Run
Time
Time (s)
Parameter
Range
Init E (V)
-10 - +10
Sample Interval (s) 1e-6 - 50
Run Time (s)
0.001 - 500000
Quiet Time (s)
0 - 100000
Scales During Run 1, 2, 3
Sensitivity (A/V)
1e-12 - 0.1
Aux. Signal Rec. Check or Uncheck
Description
Initial potential
Data sampling interval
Total measurement time
Quiescent time before potential step
Number of current display scales
Sensitivity scale
Record external signal when sample interval > 0.005 s
Electrode 2:
Potential (V)
Sensitivity (A/V)
E2 On
i2 On
Second working electrode potential
Sensitivity scale for second electrode
Second working electrode on/off control
Second working electrode current measurement on/off
-10 1e-12
Check
Check
+10
- 0.1
or Uncheck
or Uncheck
Notes
The data sampling interval should be chosen according to the length of the experiment. The longer the
experiment, the longer the sampling interval should be. A longer sampling interval results in more
signal averaging and less noise.
During an experiment, whenever the data exceed the maximum allowed points, the data storage
interval will be doubled automatically. Therefore, data points will not overflow for an unexpectedly long
experiment.
It is possible to record external voltage signals (e.g., spectroscopic signals) simultaneously with the
amperometric i-t response (minimum sampling interval may be limited). Use the 9-pin D-connector on
the rear panel for signal input. Consult the User's Manual for the pin-out and signal level requirements.
When only 1 current scale is displayed during a run, the data will be automatically scaled to fit. When
2 current scales are displayed during a run, they will be 1/100 and 1/10 of full scale. When 3 current
scales are displayed, they will be 1/100, 1/10, and 1/1 of full scale.
E2 On will turn the 2nd electrode potential control on without current sampling. This is useful if the 2nd
electrode is used for some kind of generator electrode. In order to measure current from the 2nd
channel, check i2 On.
© 2014 CH Instruments, Inc.
Setup Menu
71
4.2.15 Differential Pulse Amperometry Parameters dialog box
In Differential Pulse Amperometry (DPA), a cleaning potential can be applied for electrode conditioning,
during which current is not sampled. Two potential pulses are applied after the cleaning step, and the
current at the end of each pulse is recorded as a function of time. During the experiment, only the
difference between the two current samples is displayed. After the experiment, the current responses to
the two potential pulses will also be available for display. The following diagram shows the potential
waveform applied as a function of time and the current sampling scheme.
Potential(V)
Data Sampling
Clean E
E1
Init E
E2
Clean T
Cycle 1
0
Parameter
Init E (V)
Cleaning E (V)
Cleaning Time (s)
Pulse E1 (V)
Pulse T1 (s)
Pulse E2 (V)
Pulse T2 (s)
Number of Cycles
Quiet Time (s)
Scales During Run
Sensitivity (A/V)
Open Circ. Clean.
T1
Cycle 2
T2
Cycle 3
Time (s)
Range
-10 - +10
-10 - +10
0 - 32
-10 - +10
0.01 - 32
-10 - +10
0.01 - 32
10 - 100000
0 - 100000
1, 2, 3
1e-12 - 0.1
Check or Uncheck
Description
Initial potential
Electrode cleaning potential
Electrode cleaning time
First pulse potential
First pulse time
Second pulse potential
Second pulse time
Number of Repetitive Cycles
Quiescent time before potential pulses begin
Number of current display scales
Sensitivity scale
Cleaning step held at constant or open circuit potential
Notes
The experimental sequence consists of a cleaning step, the first pulse, and the second pulse. This
sequence is repeated until the total number of cycles is reached or the experiment is interrupted by
the user. There is no data acquisition during the cleaning step; if the cleaning time is zero, this step
will be ignored. Data are sampled for first and second pulses and the difference is reported.
Data sampling occurs during the second half-period of pulses 1 and 2. The longer the pulse width, the
longer the sample interval will be, resulting in better signal averaging and less noise.
During an experiment, whenever the data exceed the maximum allowed points, the data storage
interval will be doubled automatically. Therefore, data points will not overflow for an unexpectedly long
experiment.
When only 1 current scale is displayed during a run, the data will be automatically scaled to fit. When
2 current scales are displayed during a run, they will be 1/100 and 1/10 of full scale. When 3 current
scales are displayed, they will be 1/100, 1/10, and 1/1 of full scale.
© 2014 CH Instruments, Inc.
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CH Instruments Model 900D Series
4.2.16 Double Differential Pulse Amperometry dialog box
Double Differential Pulse Amperometry (DDPA) alternates between two instances of differential pulse
amperometry, with two sets of data recorded and displayed. In each instance, a cleaning potential can
be applied for electrode conditioning, during which current is not sampled. Two potential pulses are
applied after the cleaning step, and the current at the end of each pulse is recorded as a function of
time. During the experiment, only the difference between the two current samples is displayed. After the
experiment, the current responses to the two potential pulses will also be available for display. The
following diagram shows the potential waveform applied as a function of time and the current sampling
scheme.
Potential(V)
Data Sampling
Clean E1
Data Sampling
Clean E2
E1
E2
Init E
E3
E4
Clean T1
T1
T2
Clean T2
Cycle 1
0
Parameter
First DPA:
Cleaning E1 (V)
Cleaning Time (s)
Pulse E1 (V)
Pulse T1 (s)
Pulse E2 (V)
Pulse T2 (s)
Open Circ. Clean.
T3
T4
Cycle 2
Time (s)
Range
Description
-10 - +10
0 - 32
-10 - +10
0.01 - 32
-10 - +10
0.01 - 32
Check or Uncheck
Electrode cleaning potential
Electrode cleaning time
First pulse potential
First pulse time
Second pulse potential
Second pulse time
Cleaning step held at constant or open circuit potential
Second DPA:
Cleaning E2 (V)
Cleaning Time (s)
Pulse E1 (V)
Pulse T1 (s)
Pulse E2 (V)
Pulse T2 (s)
Open Circ. Clean.
-10 - +10
0 - 32
-10 - +10
0.01 - 32
-10 - +10
0.01 - 32
Check or Uncheck
Electrode cleaning potential
Electrode cleaning time
First pulse potential
First pulse time
Second pulse potential
Second pulse time
Cleaning step held at constant or open circuit potential
Init E (V)
Number of Cycles
Quiet Time (s)
Scales During Run
Sensitivity (A/V)
-10 - +10
10 - 100000
0 - 100000
1, 2, 3
1e-12 - 0.1
Initial potential
Number of Repetitive Cycles
Quiescent time before potential pulses begin
Number of current display scales
Sensitivity scale
Notes
The experimental sequence consists of the first DPA cleaning, a first pulse, and a second pulse,
followed by a second DPA cleaning, a third pulse, and a fourth pulse. This sequence is repeated until
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the total number of cycles is reached or the experiment is interrupted by the user. There is no data
acquisition during the cleaning steps; if the cleaning time is zero, the cleaning step will be ignored.
Data are sampled for first and second pulses and the difference is reported.
Data sampling occurs during the second half-period of pulses 1 and 2. The longer the pulse width, the
longer the sample interval will be, resulting in better signal averaging and less noise.
During an experiment, whenever the data exceed the maximum allowed points, the data storage
interval will be doubled automatically. Therefore, data points will not overflow for an unexpectedly long
experiment.
When only 1 current scale is displayed during a run, the data will be automatically scaled to fit. When
2 current scales are displayed during a run, they will be 1/100 and 1/10 of full scale. When 3 current
scales are displayed, they will be 1/100, 1/10, and 1/1 of full scale.
To specify options to display data for the first or second DPA or both, use the Graph Option command
under the Graphics menu.
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CH Instruments Model 900D Series
4.2.17 Triple Pulse Amperometry Parameters dialog box
In Triple Pulse Amperometry (TPA), three potential pulses are applied. The first two pulses are for
electrode conditioning or cleaning. Current is sampled at the end of the third potential pulse and
recorded as a function of time. The third potential pulse can be constant or incremented after each
cycle. The following diagram shows the potential waveform applied as a function of time and the current
sampling scheme.
Data Sampling
Potential(V)
E1
Init E
T1
Cycle 1
E3
E3
E3
E2
T2
T3
Cycle 2
Cycle 3
0
Time (s)
Parameter
E1 (V)
Duration 1 (s)
Open Circuit
Range
-10 - +10
0 - 32
Check or Uncheck
Description
First pulse potential
First pulse duration
Hold step 1 at open circuit or constant potential
E2 (V)
Duration 2 (s)
-10 - +10
0 - 32
Second pulse potential
Second pulse duration
E3 (V)
Duration 3 (s)
Incr E (V)
-10 - +10
0.01 - 32
0 - 0.02
Third pulse potential
Third pulse duration
Increment potential for third step
Init E (V)
Final E (V)
Number of Cycles
Quiet Time (sec)
Scales During Run
Sensitivity (A/V)
-10 - +10
-10 - +10
10 - 100000
0 - 100000
1, 2, 3
1e-12 - 0.1
Initial potential during quiescent time
Final potential for scan
Number of Repetitive Cycles
Quiescent time before taking data
Number of current display scales
Sensitivity scale
Electrode 2:
Potential (V)
Sensitivity (A/V)
On
Pulse
-10 1e-12
Check
Check
Second working electrode potential
Sensitivity scale for second electrode
Second working electrode at constant E
Step the second electrode potential
+10
- 0.1
or Uncheck
or Uncheck
Notes
The experimental sequence consists of three pulses. This sequence is repeated until the total number
of cycles is reached or the experiment is interrupted by the user. There is no data acquisition during
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the first two pulses, which are used for electrode cleaning purposes; data are sampled only for the
third pulse. If the first or second pulse time is zero, the corresponding step will be ignored.
If the increment potential is non-zero, the experiment will start at E3 and end at Final E. E3 and Final
E should be at least 0.01 V apart. The number of cycles will have no effect.
Data sampling occurs during the second half-period of pulse 3. The longer the pulse width, the longer
the sample interval will be, resulting in better signal averaging and less noise
During an experiment, whenever the data exceed the maximum allowed points, the data storage
interval will be doubled automatically. Therefore, data points will not overflow for an unexpectedly long
experiment.
When only 1 current scale is displayed during a run, the data will be automatically scaled to fit. When
2 current scales are displayed during a run, they will be 1/100 and 1/10 of full scale. When 3 current
scales are displayed, they will be 1/100, 1/10, and 1/1 of full scale.
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CH Instruments Model 900D Series
4.2.18 Integrated Pulsed Amperometric Detection Parameters dialog box
In Integrated Pulse Amperometric Detection (IPAD), six segments of potential sweeps or steps are
applied. Current is sampled and integrated during the first four segments. Electrode conditioning or
cleaning occurs during the last two steps. The integrated current is averaged and recorded as a function
of time. The following diagram shows the potential waveform applied as a function of time and the current
sampling scheme.
St 1
St 2
St 3
St 4
St 5
St 6
Potential(V)
Oxd E
Peak E
Start E
Return E
Hold E
Integration Time
Cycle 1
Red E
Cycle 2
0
Parameter
Step 1: Start
Start E (V)
Hold Time (s)
Time (s)
Range
Description
-3.276 - +3.276 Start potential (constant)
0.05 - 1
Start potential duration (current integration for last 10 ms)
Step 2: For. Scan
Peak E (V)
-3.276 - +3.276 Potential is scanned Start E to Peak E
Scan Time (s)
0.15 - 1
Potential scan time (current integration continues)
Step 3: Rev. Scan
Return E (V)
-3.276 - +3.276 Potential is scanned Peak E to Return E (often Start E)
Scan Time (s)
0.15 - 1
Potential scan time (current integration continues)
Step 4: Hold
Hold E (V)
Hold TIme (s)
-3.276 - +3.276 Hold potential (constant)
0.05 - 1
Hold potential duration (current integration for first 10 ms)
Step 5: Oxidation
Oxd E (V)
-3.276 - +3.276 Oxidation potential for electrode treatment
Oxd Time (s)
0.05 - 1
Oxidation time duration
Step 6: Reduction
Red E (V)
-3.276 - +3.276 Reduction potential for electrode treatment
Red Time (s)
0.05 - 1
Reduction time duration
Number of Cycles 5 - 65535
Quiet Time (s)
0 - 100000
Sensitivity (A/V)
1e-12 - 0.1
Number of cycles through six steps
Quiescent time before potential scan
Sensitivity scale
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Notes
The experimental sequence consists of a constant starting potential, forward potential scan, reverse
potential scan, hold potential, oxidation potential, and reduction potential. This sequence will be
repeated until the total number of cycles is reached or interrupted by the user.
Current is sampled during the last 10 msec of the start potential, forward scan, reverse scan, and the
first 10 msec of the hold potential. The current are integrated and reported.
During an experiment, whenever the data exceed the maximum allowed points, the data storage
interval will be doubled automatically. Therefore, data points will not overflow for an unexpectedly long
experiment.
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CH Instruments Model 900D Series
4.2.19 Bulk Electrolysis with Coulometry Parameters dialog box
In Bulk Electrolysis with Coulometry (BE), a constant potential is applied and the integrated charge is
recorded as a function of time. The following diagram shows the potential waveform applied as a function
of time and the sampling scheme.
Potential(V)
A preelectrolysis step can be applied to reduce interference and background current.
Sample Interval
Init E
0
Run
Time
Time (s)
Parameter
Electrolysis E (V)
End Current Ratio
Data Stor. Int. (s)
Preelec. E (V)
Preelec. T. (s)
Range
-10 - +10
0 - 100%
0.01 - 100
-10 - +10
0 - 1000000
Description
Electrolysis potential
Upper limit of potential step
Data display and storage interval
Preelectrolysis potential
Preelectrolysis time
Notes
Before electrolysis, a preelectrolysis step can be performed, which is useful for reducing residual
current. Any current at the end of preelectrolysis will be regarded as residual current and be
subtracted from the total charge to give the net charge. If preelectrolysis time is set to zero, this step
is ignored. You can stop preelectrolysis at any time by invoking the Stop command, and the regular
electrolysis will follow immediately.
The sensitivity scale will be switched automatically during the experiment.
The current ratio is reported relative to to the initial current. If the data storage interval is 1 second, the
initial current is the average current of the first second after electrolysis begins.
If the specified end current ratio is zero, electrolysis will continue forever. In order to stop the
experiment, the Stop command should be invoked.
During the experiment, the data will be updated at the same rate that data storage occurs (i.e.. will be
dictated by the data storage interval).
The data sampling interval should be chosen according to the length of the experiment. The longer the
experiment, the longer the sampling interval should be. A longer sampling interval results in more
signal averaging and less noise. However, for a thin layer cell, a short data storage time should be
chosen in order to observe the electrolysis process in detail.
During an experiment, whenever the data exceed the maximum allowed points, the data storage
interval will be doubled automatically. Therefore, data points will not overflow for an unexpectedly long
experiment.
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4.2.20 Hydrodynamic Modulation Voltammetry Parameters dialog box
Potential(V)
In Hydrodynamic Modulation Voltammetry (HMV), the potential is incremented from Init E toward Final
E. The following diagram shows the potential waveform applied as a function of time. At each potential,
the rotating speed of the RDE is modulated. The resulting alternating current is sampled and analyzed
using a software lock-in amplifier. During the experiment, only the absolute AC current is displayed.
After the experiment, the phase-selective current at any phase angle will also be available for display.
The AC current is sampled at every potential increment and recorded as a function of potential.
Final E
Init E
Incr E
Rotation speed modulation
& data sampling
Time (s)
Parameter
Init E (V)
Final E (V)
Incr E (V)
Rot. Rate (rpm)
Modul Freq. (Hz)
Modul Amp. (rpm)
Quiet Time (s)
Sensitivity (A/V)
Range
-10 - +10
-10 - +10
0.001 - 0.02
0 - 10000
1 - 5
0 - 3600
0 - 100000
1e-12 - 0.1
Description
Initial potential
Final potential
Increment potential of each step
Center rotation rate
Modulation frequency
Modulation amplitude (see Notes or Equations)
Quiescent time before potential pulses begin
Sensitivity scale
Notes
Init E and Final E should be at least 0.01 V apart.
The actual rotation rate in hydrodynamic modulation is given by ω1/2=ω01/2+∆ω1/2sin(σt)
The modulation function is a periodic waveform with modulation frequency σ but more complicated
than a sine wave. The rotation rate oscillates about ω0(rotation rate), but the amplitude of this
oscillation is not symmetric. The input parameter ∆ω (modulation frequency) is not really the
amplitude, but the square of ∆ω1/2 in the equation above.
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CH Instruments Model 900D Series
4.2.21 Sweep Step Function Parameters dialog box
In the Sweep-Step Functions technique (SSF), the instrument alternates between six potential sweeps
and six potential steps, somewhat like an arbitrary waveform generator. The following diagram shows the
potential waveform applied as a function of time. One can skip any segment by setting parameters
sufficiently small, allowing enhanced flexibility for waveform control. Current is recorded as a function of
time; for sweep segments, it can also be presented as a function of potential.
Segments:
Potential(V)
1
2
3
4
5
6
7
8
9
10
11
12
Step E
Final E
Init E
Scan Rate (V/s)
Time (s)
Parameter
Seq. 1,3,5,7,9,11
Sweep:
Init E (V)
Final E (V)
Scan Rate (V/s)
Range
Description
-10 - +10
-10 - +10
1e-4 - 50
Initial potential
Final potential
Potential scan rate
Seq. 2,4,6,8,10,12
Step:
Step E (V)
-10 - +10
Step Time (s)
0 - 10000
Step potential
Step duration
Init E (V)
Sweep S.I. (V)
Step S.I. (s)
Quiet Time (s)
Sensitivity (A/V)
Initial potential
Sweep function sampling interval
Step function sampling interval
Quiescent time before potential scan
Sensitivity scale
-10 - +10
0.001 - 0.05
0.0001 - 1
0 - 100000
1e-12 - 0.1
Notes
A Sweep sequence will be ignored if the difference between its Init E and Final E is less than 0.01 V.
A Step sequence will be ignored if its step time is less than 0.001 sec or its number of points is less
than 3. To remedy the latter case, either increase its step time or decrease its sampling interval.
If the scan rate for a Sweep sequence is less than 0.5 V/s, data will be transferred and displayed in
real time.
If the sampling interval for a Step sequence is larger than 0.002 sec, data will be transferred and
displayed in real time.
The potential differences between Init E, Final E, and Step E should be less than 13.1 V.
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4.2.22 Multi-Potential Steps Parameters dialog box
In the Multi-Potential Steps technique (STEP), twelve potential steps can be applied and cycled. Current
is recorded as a function of time. The following diagram shows the potential waveform applied as a
function of time.
Potential(V)
Steps:
1 2 3 4 5 6 7 8 9 10 11 12
Cycle 1
Cycle 2
Time (s)
Parameter
Step Seq. 1-12
Step E (V)
Step Time (s)
Range
Description
-10 - +10
0 - 10000
Step potential
Step duration
Init E (V)
No. of Cycles
Smpl Intv (s)
Quiet Time (s)
Sensitivity (A/V)
E1 On
-10 - +10
1 - 10000
0.0001 - 1
0 - 100000
1e-12 - 0.1
Check or Uncheck
Initial potential
Number of cycles
Sampling interval
Quiescent time before potential scan
Sensitivity scale
Working electrode 1 on/off control
Notes
A step will be ignored if its step time is less than 0.001 sec or shorter than its sampling interval.
If the sampling interval for a Step sequence is larger than 0.002 sec, data will be transferred and
displayed in real time.
The sampling interval will be automatically increased if (step time * cycles / sample interval) exceeds
64K if data is to be transferred after the experiment.
If the sampling interval is larger than 0.002 sec, data will be transferred and displayed in real time.
The potential difference between Init E, Final E, and Step E should be less than 13.1 V.
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CH Instruments Model 900D Series
4.2.23 A.C. Impedance Parameters dialog box
Potential(V)
In the AC Impedance technique (IMP), the base potential is held constant at Init E. A sine waveform is
superimposed onto the base potential, and its frequency is scanned from high to low with 12
components per decade. Current and potential are sampled and analyzed to obtain the real and
imaginary parts of the impedance. During the experiment, you can switch between a Bode plot and a
Nyquist plot by right-clicking. After the experiment, impedance data can be presented in various forms.
The following diagram shows the potential waveform applied as a function of time.
Amplitude
Init E
High Freq
Low Freq
Time (s)
Parameter
Init E (V)
High Freq. (Hz)
Low Freq. (Hz)
Amplitude (V)
Quiet Time (s)
Sensitivity Scale
Meas. Mode
Avrg (1K-1M Hz)
Avrg (1-999 Hz)
Cycles (0.1-1 Hz)
Cycles (0.01-0.1)
Cycles (1e-3-1e-2)
Cycles (1e-4-1e-3)
Cycles (1e-5-1e-4)
Points (all freqs)
Bias DC Current
Range
-10 - +10
1e-4 - 2e6
1e-5 - 1e5
1e-5 - 0.7
0 - 100000
Select
FT - Single - Galv.
0.1 - 4
1 - 256
1 - 25
1 - 25
1 - 25
1 - 16
1 - 4
0 - 100
off - range - on
Description
Initial potential
High frequency limit
Low frequency limit
A.C. amplitude
Quiescent time before potential scan
Automatic or Manual
Select measurement mode above 100 Hz
Average factors
Average factors
Number of cycles at each frequency point
Number of cycles at each frequency point
Number of cycles at each frequency point
Number of cycles at each frequency point
Number of cycles at each frequency point
Number of points per decade frequency
Enable DC current bias during run
Notes
Above 100 Hz, both current and potential are measured in order to calculate impedance. 12 frequency
components per decade will be measured. In the Fourier transform case, each measurement covers a
decade of frequency range. Below 100 Hz, only current is measured. The applied potential is assumed
to have no extra phase shift and be accurate.
When DC current is high and AC current is low, sensitivity cannot be increased because the DC
current will overflow. This problem is more serious when the frequency is relatively low. The application
of a DC current bias allows higher AC signal amplification. A 16-bit DAC is used for this purpose. On
the other hand, if the DC current is not expected to be large and the frequency is high, a DC current
bias may be unnecessary.
The power line frequency (50 or 60 Hz, depending on your region) can interfere with measurements.
Use a longer measurement time between 1-100Hz to improve data quality of this frequency range.
© 2014 CH Instruments, Inc.
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Automatic sensitivity scale is used by default. The sensitivity scale setting can also be manually
overridden by clicking the Manual button top open the Manual Sensitivity Setting dialog box.
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CH Instruments Model 900D Series
4.2.24 Impedance - Time Parameters dialog box
Potential(V)
In the Impedance - Time technique (IMPT), the base potential is held constant at Init E, onto which a
sine waveform is superimposed. Current and potential are sampled and analyzed to obtain the real and
imaginary parts of the impedance as a function of time. The following diagram shows the potential
waveform applied as a function of time.
Amplitude
Sample Interval
Init E
Run Time
Time (s)
Parameter
Range
Init E (V)
-10 - +10
Amplitude (V)
0.0001 - 1.5
Frequency (Hz)
0.0001 - 1e6
Sample Interval (s) 1 - 20000
Run Time (s)
1 - 500000
Cycles (< 10 Hz)
1 - 100
Quiet Time (s)
0 - 100000
Bias DC Current
off - range - on
Sensitivity Scale 1e-12 - 0.1
Description
Initial potential
A.C. amplitude
A.C. frequency
Data sampling interval
Total experiment time
Number of repetitive cycles at each frequency
Quiescent time before sampling data
Enable DC current bias during run
Sensitivity scale (automatic or manual)
Notes
If the sampling interval is smaller than the actual time required for sampling, it will be automatically
adjusted.
More cycles result in a better signal-to-noise ratio but also a longer experiment run time.
When DC current is high and AC current is low, sensitivity cannot be increased because the DC
current will overflow. This problem is more serious when the frequency is relatively low. The application
of a DC current bias allows higher AC signal amplification. A 16-bit DAC is used for this purpose. On
the other hand, if the DC current is not expected to be large and the frequency is high, a DC current
bias may be unnecessary.
Automatic sensitivity scale is used by default. During the experiment, the system tests the current
size and determines the proper sensitivity scale. This usually works pretty well. The sensitivity scale
setting can also be manually overridden, which may yield better results in certain cases.
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4.2.25 Impedance - Potential Parameters dialog box
Potential(V)
In the Impedance - Potential technique (IMPE), the base potential is incremented from Init E toward Final
E, onto which a sequential sine waveform is superimposed. Current and potential are sampled and
analyzed to obtain the real and imaginary parts of the impedance as a function of potential. The following
diagram shows the potential waveform applied as a function of time.
Incr E
Final E
Amplitude
Init E
One Cycle
Time (s)
Parameter
Init E (V)
Final E (V)
Incr E (V)
Amplitude (V)
Frequency (Hz)
Cycles (< 10 Hz)
Quiet Time (s)
Bias DC Current
Sensitivity Scale
Range
-10 - +10
-10 - +10
0.001 - 0.25
0.001 - 1.5
0.0001 - 1e5
1 - 100
0 - 100000
off - range - on
1e-12 - 0.1
Description
Initial potential
Final potential
Increment potential
A.C. amplitude
A.C. frequency
Number of repetitive cycles at each frequency
Quiescent time before sampling data
Enable DC current bias during run
Sensitivity scale (automatic or manual)
Notes
When DC current is high and AC current is low, sensitivity cannot be increased because the DC
current will overflow. This problem is more serious when the frequency is relatively low. The application
of a DC current bias allows higher AC signal amplification. A 16-bit DAC is used for this purpose. On
the other hand, if the DC current is not expected to be large and the frequency is high, a DC current
bias may be unnecessary.
Automatic sensitivity scale is used by default. During the experiment, the system tests the current
size and determines the proper sensitivity scale. This usually works pretty well. The sensitivity scale
setting can also be manually overridden, which may yield better results in certain cases.
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CH Instruments Model 900D Series
4.2.26 Chronopotentiometry Parameters dialog box
In Chronopotentiometry (CP), two current levels can be specified to pass through the working electrode,
with the switching between the two dictated by time or potential. Potential is recorded as a function of
time. The following diagram shows the current waveform applied as a function of time.
Current (A)
Anodic Current
Cathodic Time
Anodic Time
Cathodic Current
Cathodic Current
Segment 1
0
Parameter
Range
Cathodic Curr. (A) -2 - +2
Anodic Current (A) -2 - +2
High E Limit (V)
-10 - +10
High E Hold T. (s) 0 - 100000
Low E Limit (V)
-10 - +10
Low E Hold T. (s) 0 - 100000
Cathodic Time (s) 0.005 - 100000
Anodic Time (s)
0.005 - 100000
Initial Polarity
Cathodic/Anodic
Data Stor. Intvl (s) 0.0001 - 500
Num. of Segments 1 - 1000000
Curr. Switch. Prior.Potential or Time
Aux. Signal Rec. Check or Uncheck
Cathodic Time
Segment 2
Segment 3
Time (s)
Description
Controlled cathodic current
Controlled anodic current
High potential limit
High potential hold time
Low potential limit
Low potential hold time
Cathodic run time
Anodic run time
Polarity for the first segment
Data storage interval
Number of half cycles
Current polarity switching control
Simult. record external signal when samp. interval >= 0.0005 s
Notes
Cathodic and anodic currents correspond to reduction and oxidation, respectively. When the Low E
limit is reached during reduction, the current polarity will automatically be switched to anodic.
Similarly, when the High E Limit is reached during oxidation, current will automatically be switched to
cathodic. When the number of current polarity switches (Segments) is reached, the experiment stops.
The Initial Polarity parameter specifies the initial current polarity.
During the experiment, data update and storage rates will be the same (i.e., dictated by the Data
Storage Intvl parameter).
The data sampling interval should be chosen according to the length of the experiment. The longer the
experiment, the longer the sampling interval should be.
During an experiment, whenever the data exceed the maximum allowed points, the data storage
interval will be doubled automatically. Therefore, data points will not overflow for an unexpectedly long
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experiment.
A large number of segments can be specified, but data will only be stored for the first 400 segments.
Later segments will be displayed during the run but not stored.
The current polarity can be switched when either the specified potential or the specified time has been
reached. The switching time can be different for cathodic and anodic switching. Note, however, that
even with Time switching selected, if the limiting potential is reached, the current polarity will still be
reversed in order to protect the electrode.
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CH Instruments Model 900D Series
4.2.27 Chronopotentiometry with Current Ramp Parameters dialog box
In the Chronopotentiometry with Current Ramp technique (CPCR), a current ramp is applied to the
working electrode, and potential is recorded as a function of time. The following diagram shows the
current waveform applied as a function of time.
Current (A)
Final Current
Scan Rate (A/s)
Init Current
Time (s)
Parameter
Init Current (A)
Final Current (A)
Scan Rate (A/s)
High E Limit (V)
Low E Limit (V)
Data Stor. Intvl (s)
Range
-2 - +2
-2 - +2
1e-12 - 0.1
-10 - +10
-10 - +10
0.0001 - 500
Description
Controlled cathodic current
Controlled anodic current
Current scan rate
High potential limit
Low potential limit
Data storage interval
Notes
Initial Current and Final Current should be at least 1e-9A apart.
Cathodic and anodic currents correspond to reduction and oxidation, respectively. If the High E or Low
E limit is reached during reduction, the experiment stops.
At least 10 points are required to run the experiment. Reduce the current scan rate or reduce the
sampling interval as needed to meet this requirement.
During the experiment, data update and storage rates will be the same (i.e., dictated by the Data
Storage Intvl parameter).
The data sampling interval should be chosen according to the length of the experiment. The longer the
experiment, the longer the sampling interval should be.
During an experiment, whenever the data exceed the maximum allowed points, the data storage
interval will be doubled automatically. Therefore, data points will not overflow for an unexpectedly long
experiment.
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4.2.28 Multi-Current Steps Parameters dialog box
In the Multi-Current Steps technique (ISTEP), up to twelve current steps can be applied and cycled.
Potential is recorded as a function of time. The following diagram shows the current waveform applied as
a function of time.
Steps:
Current (A)
1 2 3 4 5 6 7 8 9 10 11 12
Cycle 1
Cycle 2
Time (s)
Parameter
Step Seq. 1-12
Step i (A)
Step Time (s)
Range
Description
-2 - +2
0 - 10000
Step current
Step duration
High E Limit (V)
Low E Limit (V)
No. of Cycles
Smpl Intv (s)
-10
-10
1 1e-5
High potential limit
Low potential limit
Number of cycles
Sampling interval
- +10
- +10
10000
- 1
Notes
A step with duration less than 0.001 sec or shorter than the sampling interval will be ignored.
If the sampling interval is longer than 0.002 sec, data will be transferred and displayed in real time.
The experiment will stop if the potential reaches either High E Limit or Low E Limit.
The sampling interval will be automatically increased if (step time * cycles / sample interval) exceeds
128K if data is to be transferred after the experiment.
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CH Instruments Model 900D Series
4.2.29 Potentiometric Stripping Analysis Parameters dialog box
Potential (V) or Current (A)
In Potentiometric Stripping Analysis (PSA), a constant potential deposition step is first applied, after
which the species accumulated at the electrode surface are stripped out by applying a constant current.
Potential is recorded as a function of time. The following diagram shows the potential waveform during
the deposition stage and the current waveform during the stripping stage.
Data Storage Interval
Stripping Current
Deposition E
Deposition Time
0
Parameter
Range
Deposition E (V)
-10 - +10
Deposit. Time (s) 0 - 1000000
Final E (V)
-10 - +10
Stripping Curr. (A) 0 - 2
Sample Interval (s) 0.0001 - 50
Quiet Time (s)
0 - 100000
Time (s)
Description
Deposition potential
Deposition time
Final potential (see Notes)
Controlled stripping current
Sampling interval
Quiescent time before taking data
Notes
If sample interval is less than 0.002 s, a total of 64K data points is allowed. The data density is equal
to Run Time / 64000.
If the final potential is reached, the experiment will automatically stop.
If the controlled stripping current is set to zero, the counter electrode is actually not connected.
If the controlled stripping current is smaller than 1.0e-10A, no current will flow during experiment.
You do not have to worry about the current polarity; the system will automatically assign the current
polarity according to the deposition potential and the final potential. Positive and negative current
correspond to reduction and oxidation, respectively.
In general, the data storage interval should be chosen according to the length of the experiment. The
longer the experiment, the longer the data storage interval should be.
© 2014 CH Instruments, Inc.
Setup Menu
91
4.2.30 Parameters for Open Circuit Potential vs Time dialog box
In the Open Circuit Potential - Time technique (OCPT), the working and reference electrodes are
connected and the potential difference across them is recorded as a function of time. Since the counter
electrode is not connected to the external cell, no current passes through the working electrode except
the bias current of the measuring amplifiers, which is in the picoamperes range.
The program presents the following dialog box:
Parameter
Range
Run Time (s)
1 - 500000
Sample Interval (s) 0.0025 - 50
High E Limit (V)
-10 - +10
Low E Limit (V)
-10 - +10
Description
Experiment running time
Sampling interval
High potential limit
Low potential limit
Notes
If the high or low potential limit is reached, a warning will be given.
In general, the data storage interval should be chosen according to the length of the experiment. The
longer the experiment, the larger the data storage interval.
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CH Instruments Model 900D Series
4.2.31 Parameters for Electrochemical Noise Measurement dialog box
In Electrochemical Noise measurements (ECN), no waveform is applied to the electrochemical cell. The
working electrode is at the zero-resistance ammeter, and its potential is at virtual ground (very close to
ground; it cannot be connected to a true ground). To measure electrochemical noise, an electrode
identical to the working electrode should be connected to the instrument ground (the black banana jack
on the rear panel labeled GND), and both electrodes should be immersed in the same solution. The
electrochemical noise current passing through these two electrodes will be measured. To measure
potential noise, add a reference electrode to the solution and connected it to the reference clip. The
counter electrode will not be used.
The system displays the following dialog box:
Parameter
Range
Sample Interval (s) 0.1 - 10
Run Time (s)
10 - 100000
Quiet Time (s)
0 - 100000
Sensitivity (A/V)
1e-9 - 0.1
Potential Gain
1, 10, 100, 1000
Meas. Mode
i, E, or both
Description
Sampling interval
Experiment running time
Quiescent time before potential pulses begin
Sensitivity scale
Gain setting for potential noise measurement
Measurement mode
© 2014 CH Instruments, Inc.
Setup Menu
93
4.2.32 Surface Patterned Conditioning Parameters dialog box
This technique is used to condition the SECM substrate surface with a pattern, e.g., for
micromachining.
For instance, the SECM probe can be scanned across the surface and held at either E1 or E2 at
rectilinear grid points as dictated by the specified pattern. If a reaction occurs at E1 but not E2 (or vice
versa), then deposition/etching will occur at the patterned points. The Create New Pattern button opens
the graphical pattern editor; please refer to the Notes below for more details.
The program presents a Surface Patterned Conditioning Parameters dialog box:
Parameter
Probe E1 (V)
Hold Time 1 (s)
Probe E2 (V)
Hold Time 2 (s)
Sensitivity (A/V)
Range
-10 - +10
0 - 4000
-10 - +10
0 - 4000
1e-12 - 0.1
Description
First probe potential
Hold time at first probe potential
Second probe potential
Hold time at first probe potential
Probe sensitivity scale
Substrate E1 (V)
Substrate E2 (V)
Sensitivity (A/V)
E On
-10 -10 1e-12
Check
First substrate potential
Second substrate potential
Substrate sensitivity scale
Substrate potential on/off control
X Distance (um)
-50000 - 50000 Probe travel distance in X direction
© 2014 CH Instruments, Inc.
+10
+10
- 0.1
or Uncheck
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CH Instruments Model 900D Series
Y Distance (um)
Incr. Dist. (um)
-50000 - 50000 Probe travel distance in Y direction
0.0001 - 100
Probe increment distance during scan
Create New Patt.
Return to Origin
Motor Selection
Long Travel Dir.
Button
Check or Uncheck
Select
X or Y
Click to create new pattern
Return probe to origin after conditioning
Auto, Stepper, or Piezo
Select the long move direction
Notes
In this technique, a new pattern needs to be created by using the Create New Pattern button. The
pattern size and pixel size are determined by the X/Y distances and the increment distance in the
Probe Travel section. The “Create New Pattern” button can also be used to clear an existing pattern.
A new pattern is created with all dark pixels. Left-click and drag to create a trace of bright pixels. To
erase bright pixels, right-click and drag. You can create a bitmap pattern for surface conditioning this
way.
A dark pixel represents "0". It puts the probe and substrate (if turned on) at their respective first
potentials E1 for Hold Time 1.
A bright pixel represents "1". It puts the probe and substrate (if turned on) at their respective second
potentials E2 for Hold Time 2.
Sensitivity should be chosen high enough so that the current at each pixel can be displayed correctly
during a run, but not so high that overflow occurs. Overflow will affect the accuracy of potential control,
and it is safer to set a relatively low sensitivity. If the sensitivity setting is too low, the current reading
may not be accurate. Nevertheless, this will not affect the surface patterned conditioning results.
If both X and Y distances are within the X and Y piezo range, automatic motor selection will choose
the piezo positioner. Otherwise, the stepper motors will be used.
If the piezo positioner is selected but the X or Y distance exceeds the piezo range, the stepper motors
will be used instead.
A maximum of 512 × 512 pixels per image is allowed. If the number of data point in a dimension
exceeds 512, its increment distance will be automatically adjusted.
X and Y distances cannot be zero. At least two points are needed in each direction.
© 2014 CH Instruments, Inc.
Setup Menu
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4.2.33 Probe Scan Curve Parameters dialog box
In this technique, the SECM probe is scanned in the X, Y, or Z direction, and the resulting probe and/or
substrate current is measured.
Both the potential and sensitivity of the probe and substrate electrode can be controlled independently.
The probe electrode can also be subjected to a pulse of specified potential and duration for
electrochemical cleaning prior to data sampling. The substrate electrode can be turned on or off. Scan/
increment distance and increment (sampling) time can also be specified. Optionally, a probe scan can
be aborted if the measured current exceeds the specified thresholds, for the purpose of probe protection.
Several measurement modes are available. When performed in the X or Y direction, amperometry,
potentiometry, and impedance modes maintain constant probe height.
Amperometry: measure probe current as a function of position
Potentiometry: measure probe potential as a function of position
Constant current: measure probe height as a function of position
Height (Z) will be adjusted automatically to maintain current constant.
If the sample or substrate is an insulator, the resulting plot yields topographic information.
Current value and tolerance must be specified.
Impedance: measure probe impedance as a function of position
AC frequency and amplitude must be specified.
In a Z direction scan, the impedance will increase sharply when approaching the surface. thus allowing
a close probe approach without a redox mediator in solution.
The program presents the following dialog box:
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CH Instruments Model 900D Series
Parameter
Probe E (V)
Sensitivity (A/V)
Range
-10 - +10
1e-12 - 0.1
Description
First probe potential
Probe sensitivity scale
Pulse E (V)
-10 - +10
Pulse Duration (s) 0 - 10
Delay time (s)
0.1 - 50
E1 Pulse On
Check or Uncheck
Probe pulse potential
Pulse duration
Delay time after pulse before sampling
Probe pulse potential on/off
Substrate E (V)
Sensitivity (A/V)
E2 On
i2 On
-10 1e-12
Check
Check
Substrate potential
Substrate sensitivity scale
Substrate potential on/off
Substrate current measurement on/off
Probe Stop...
No
Abs. Current (A)
Select or Unselect Manually stop probe motion
0 - 0.01
Probe will stop at the specified current threshold
Mode
Frequency (Hz)
Amplitude (V)
Bias DC Current
AutoSens
Select
1 - 1000000
1e-5 - 0.7
Check or Uncheck
Check or Uncheck
Amperometry, potentiometry, constant current, or impedance
AC frequency
AC amplitude
Enable DC current bias during run
Enable automatic sensitivity scale (impedance only)
Scan Direction
Const. Current (A)
Current Tolerance
Max Z Incr (um)
Select
5e-12 - 1e-8
0.01% - 5%
0.0001 - 10
Scan X, Y, or Z direction
Constant current control value
Allowed current tolerance for constant current control
Maximum increment in Z direction
+10
- 0.1
or Uncheck
or Uncheck
© 2014 CH Instruments, Inc.
Setup Menu
Motor Selection
Travel Dist. (um)
Incr. Dist. (um)
Incr Time (s)
Quiet Time (s)
Select
-50000 - 50000
0.001 - 100
0.002 - 60
0 - 100000
97
Auto, stepper, or piezo
Probe travel
Probe increment distance during scan
Increment or sampling time
Quiescent time before probe move
Notes
When E2 On is checked, the substrate potential will be turned on but no current will be measured.
When i2 On is checked, the substrate potential will be turned on and current will be measured.
The probe can be stopped either manually or at an absolute current level, depending on the selection
made in the Probe Stop at Current Level area.
The travel distance cannot be set to zero.
The options in the Probe E Pulse before Sampling area can be used for electrode cleaning purposes
during an experiment. If "E1 Pulse On" is unchecked, this feature will be ignored.
If both X and Y distances are within the X and Y piezo range, automatic motor selection will choose
the piezo positioner. Otherwise, the stepper motors will be used.
If the piezo positioner is selected but the X or Y distance exceeds the piezo range, the stepper motors
will be used instead.
To reduce interference from the (power) line frequency, the sampling period (via Incr Time) should be a
multiple of the reciprocal of the line frequency. For instance, if the line frequency is 60 Hz, an Incr
Time of 0.01667, 0.03333, 0.05, 0.06667, 0.08333, 0.1, etc. is recommended. If the line frequency is
50 Hz, an Incr Time divisible by 0.02 is recommended.
In Constant Current mode, negative (positive) height indicates that the tip has moved upward
(downward). Before the measurement, the Z piezo will be set to its middle position, and the specified
constant current level will be reached with a combination of stepper motor and piezo movements.
Once the scan starts, only the Z piezo will be adjusted to keep the current constant. Since the Z
piezo has a maximum range of about 80 microns and its start position is at the middle, its maximum
adjustable range is ±40 microns. If a Z move exceeds ±40 microns, a warning will appear and the scan
will be terminated.
At the end of a scan in Constant Current mode, the Z piezo will be set back to the zero position.
Constant Current mode is not available for a Z probe scan curve.
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CH Instruments Model 900D Series
4.2.34 Probe Approach Curve Parameters dialog box
This technique (carefully) moves the SECM probe towards the surface of the substrate and measures
the resulting current response.
Probe current is always measured; the substrate electrode can be optionally monitored. Both the
potential and sensitivity of the probe and substrate electrode can be controlled independently. The probe
electrode can also be subjected to a pulse of specified potential and duration for electrochemical
cleaning prior to data sampling. The substrate electrode can be turned on or off. The maximum
increment distance, the increment (sampling) time, and the probe current ratio or absolute current level
for approach to stop can also be specified as listed below. Please refer to the Notes below for more
details.
The program presents the following dialog box:
Parameter
Probe E (V)
Sensitivity (A/V)
Range
-10 - +10
1e-12 - 0.1
Description
First probe potential
Probe sensitivity scale
Pulse E (V)
-10 - +10
Pulse Duration (s) 0 - 10
Delay time (s)
0.1 - 50
E1 Pulse On
Check or Uncheck
Probe pulse potential
Pulse duration
Delay time after pulse before sampling
Probe pulse potential on/off
Substrate E (V)
Sensitivity (A/V)
E2 On
i2 On
-10 1e-12
Check
Check
Substrate potential
Substrate sensitivity scale
Substrate potential on/off
Substrate current measurement on/off
Motor Selection
Select
+10
- 0.1
or Uncheck
or Uncheck
Auto, stepper, or piezo
© 2014 CH Instruments, Inc.
Setup Menu
Approach Speed
Ratio (%)
Absolute (A)
Select
1 - 1000
0 - 0.01
Normal or fast
Current ratio threshold
Current level threshold
Max Incr (um)
With. Dist. (um)
Incr Time (s)
Quiet Time (s)
0.0001 - 1
0 - 10000
0.001 - 0.2
0 - 100000
Maximum increment of probe when approaching surface
Probe withdraw distance before surface approach
Increment or sampling time
Quiescent time before probe approach
99
Notes
When E2 On is checked, the substrate potential will be turned on but no current will be measured.
When i2 On is checked, the substrate potential will be turned on and current will be measured.
The probe can be stopped either manually or at an absolute current level, depending on the selection
made in the Probe Stop at Current Level area.
If the Current Ratio parameter is lower than 100% but the current increases as the probe approaches
the (e.g., conducting) surface, a default value of 125% will be used instead. If the Current Ratio
parameter is higher than 100% but the current decreases as the probe approaches the (e.g.,
insulating) surface, a default value of 75% will be used instead.
PID control (Proportional-Integral-Derivative) is used for the probe approach. The tip moves faster (i.e.,
moves with bigger increments) when the tip is far away from the surface and slows down (i.e., moves
with smaller increments) when the tip is closer to the surface and the system senses a change in the
tip current. PID control reduces the risk of tip overshoot (collision with the sample) and consequent
sample and/or tip damage. The maximum increment should be set according to the probe size--the
smaller the probe diameter, the smaller the increment should be.
Before the probe moves toward the surface, it will move backward for by Withdraw Distance.
The options in the Probe E Pulse before Sampling area can be used for electrode cleaning purposes
during an experiment. If “E1 Pulse On” is unchecked, this feature will be ignored.
Normal approach speed should be used if the probe approach curve is to be recorded for data analysis
purposes or if the probe is already close to the surface. Fast approach speed can be used for a
quicker probe approach, without causing the probe to touch the surface. This is useful when the probe
is far away from the surface.
If Automatic motor selection is selected, the stepper motor will be used if the increment is greater
than 0.1 micron. Otherwise, the piezo will be used.
If the piezo positioner is selected but the travel distance exceeds the piezo range, a warning will
appear and the approach will stop.
To reduce interference from the (power) line frequency, the sampling period (via Incr Time) should be a
multiple of the reciprocal of the line frequency. For instance, if the line frequency is 60 Hz, an Incr
Time of 0.01667, 0.03333, 0.05, 0.06667, 0.08333, 0.1, etc. is recommended. If the line frequency is
50 Hz, an Incr Time divisible by 0.02 is recommended.
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CH Instruments Model 900D Series
4.2.35 Surface Interrogation SECM Parameters dialog box
In this technique, the potential of the substrate electrode, which should be about the same size and
positioned close to the probe, is first swept or stepped to adsorb or electrochemically generate a
species of interest, with the probe electrode at open circuit. Then the substrate electrode is
disconnected (at open circuit), and the probe electrode potential is swept or stepped to
electrochemically generate a titrant from a reversible redox mediator. This titrant reacts in situ with the
species generated during the first step, resulting in a transient positive feedback loop until the adsorbate
is consumed completely. The current response is recorded.
The program presents the following dialog box:
Parameter
Substrate
Electrode:
Init E (V)
Final E (V)
Segments
Quiet Time (s)
Sensitivity (A/V)
Sweep/Step
Scan Rate (V/s)
Sample Int. (V)
Pulse Width (s)
Sample Int. (s)
Probe Electrode:
Init E (V)
Final E (V)
Segments
Quiet Time (s)
Sensitivity (A/V)
Range
Description
-10 - +10
-10 - +10
1 - 320
0 - 50000
1e-12 - 0.1
Select
1e-6 - 3
0.001 - 0.02
0.01 - 1000
0.0005 - 10
Initial substrate electrode potential
Final substrate electrode potential
Number of half-cycles
Quiescent time before run
Substrate sensitivity scale
Potential control: linear sweep or pulsed step
Potential scan rate (Sweep only)
Data sampling interval (Sweep only)
Duration of potential step (Step only)
Data sampling interval (Step only)
-10 - +10
-10 - +10
1 - 100
-10 - +10
1e-12 - 0.1
Initial probe electrode potential
Final probe electrode potential
Number of half-cycles
Quiescent time before run
Probe sensitivity scale
© 2014 CH Instruments, Inc.
Setup Menu
Sweep/Step
Scan Rate (V/s)
Sample Int. (V)
Pulse Width (s)
Sample Int. (s)
Select
1e-6 - 3
0.001 - 0.02
0.01 - 1000
0.0005 - 10
Action b/w Two
Runs
Delay
OCP
Select
© 2014 CH Instruments, Inc.
0 - 10000
-10 - 10
Potential control: linear sweep or pulsed step
Potential scan rate (Sweep only)
Data sampling interval (Sweep only)
Duration of potential step (Step only)
Data sampling interval (Step only)
Delay in seconds
Initiate second run at Open Circuit Potential
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CH Instruments Model 900D Series
4.2.36 Scanning Electrochemical Microscope Parameters dialog box
In the general SECM experiment, the probe electrode is scanned across the XY plane, and a probe
response is recorded and plotted as a function of X and Y to yield an SECM image.
Typically the image will be generated from the probe electrode response, but the substrate electrode
response can also be used in amperometry mode. The probe and substrate electrode potential and
current sensitivity can be controlled independently; time and distance increments and the scan distance
can also be specified.
Several measurement modes are available. When performed in the X or Y direction, amperometry,
potentiometry, and impedance modes maintain constant probe height.
Amperometry: measure probe current as a function of position
Potentiometry: measure probe potential as a function of position
Constant current: measure probe height as a function of position
Height (Z) will be adjusted automatically to maintain current constant.
If the sample or substrate is an insulator, the resulting plot yields topographic information.
Current value and tolerance must be specified.
Impedance: measure probe impedance as a function of position
AC frequency and amplitude must be specified.
In a Z direction scan, the impedance will increase sharply when approaching the surface. thus allowing
a close probe approach without a redox mediator in solution.
During an SECM experiment, the program will display a greyscale or color-coded 2-d plot of the XY
plane in real time. Interactive 3-d plots (rotate, zoom, etc.) are available from the Graph Options menu
once the experiment has completed.
The program presents the following dialog box:
© 2014 CH Instruments, Inc.
Setup Menu
Parameter
Probe E (V)
Quiet Time (s)
Sensitivity (A/V)
Range
-10 - +10
1 - 100000
1e-12 - 0.1
Description
First probe potential
Quiescent time before data sampling
Probe sensitivity scale
Substrate E (V)
Sensitivity (A/V)
E On
i2 On
-10 1e-12
Check
Check
+10
- 0.1
or Uncheck
or Uncheck
Substrate potential
Substrate sensitivity scale
Substrate potential on/off
Substrate electrode imaging on/off
X Distance (um)
Y Distance (um)
Incr. Dist. (um)
Incr Time (s)
-50000
-50000
0.0001
0.002
- 50000 Probe travel distance in X direction
- 50000 Probe travel distance in Y direction
- 100
Probe distance increment during scan
- 60
Probe time increment (sampling time)
SECM Mode
Select
Const. Current (A) 5e-12 - 1e-8
Current Tolerance 0.01% - 5%
Max Z Incr (um)
0.0001 - 10
Amperometry (constant height), potentiometry, constant
current, or impedance
Constant current control value
Allowed current tolerance for constant current control
Maximum allowed Z step size for current adjustment
Impedance Mode:
Frequency (Hz)
Amplitude (V)
Bias DC Current
AutoSens
AC frequency
AC amplitude
Bias DC current during measurement to increase AC gain
Enable automatic sensitivity scale (impedance only)
1 - 1000000
0.0001 - 0.7
Check or Uncheck
Check or Uncheck
Motor Selection
Select
X / Y Axis as Long Select
Return to Origin
© 2014 CH Instruments, Inc.
Auto, stepper, or piezo
Specify long move direction
Check or Uncheck Move probe back to origin after imaging
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CH Instruments Model 900D Series
Notes
A maximum of 512 × 512 pixels per image is allowed. If the number of data point in a dimension
exceeds 512, its increment distance will be automatically adjusted.
When E2 On is checked, the substrate potential will be turned on but no current will be measured.
When i2 On is checked, the substrate potential will be turned on and current will be measured.
X/Y distance cannot be zero.
If both X and Y distances are within the X and Y piezo range, automatic motor selection will choose
the piezo positioner. Otherwise, the stepper motors will be used.
If the piezo positioner is selected but the X or Y distance exceeds the piezo range, the stepper motors
will be used instead.
To reduce interference from the (power) line frequency, the sampling period (via Incr Time) should be a
multiple of the reciprocal of the line frequency. For instance, if the line frequency is 60 Hz, an Incr
Time of 0.01667, 0.03333, 0.05, 0.06667, 0.08333, 0.1, etc. is recommended. If the line frequency is
50 Hz, an Incr Time divisible by 0.02 is recommended.. If the line frequency is 50 Hz, Incr Time of
0.02s and its multiples are recommended.
In Constant Current mode, negative (positive) height indicates that the tip has moved upward
(downward). Before the measurement, the Z piezo will be set to its middle position, and the specified
constant current level will be reached with a combination of stepper motor and piezo movements.
Once the scan starts, only the Z piezo will be adjusted to keep the current constant. Since the Z
piezo has a maximum range of about 80 microns and its start position is at the middle, its maximum
adjustable range is ±40 microns. If a Z move exceeds ±40 microns, a warning will appear and the scan
will be terminated.
At the end of a scan in Constant Current mode, the Z piezo will be moved back to its zero position.
© 2014 CH Instruments, Inc.
Setup Menu
4.3
105
System command
This command opens the System Setup dialog box.
Use this command to set up the serial communication port, current polarity, potential axis and current
axis. You can choose any convention for the potential and current axis.
The System command presents this dialog box.
The following options allow you to set up your system:
Communication Port
Select the PC communication port to which the instrument is linked. This setting is required to establish
communication between your PC and your instrument. If it is not set correctly, you will not be able to
control your instrument. Available ports should be listed in the Windows Device Manager.
If you are using the "Automatically detect Com port" option, you will not need to change this setting.
Com Port Speed
Set the communication speed between the PC and the instrument. The Fast setting allows real time
data transfer at higher scan rate and/or shorter sampling interval. The Standard setting is included for
greater compatibility. This setting is not available on older instruments.
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CH Instruments Model 900D Series
Current Polarity
Assign anodic or cathodic current as positive-valued. This sign convention must be chosen before
running an experiment; otherwise, experimental results (peaks, waves) will not be reported properly.
Potential Axis
Assign left or right as the positive direction for the potential axis (only applicable to voltammetric or
polarographic techniques).
Current Axis
Assign up or down as the positive direction for the current axis.
Line Frequency
Select the correct (power) line frequency for your geographic region. This will reduce interference from
the line frequency by adjusting the default sampling interval in certain techniques.
Windows
Select the language used by your Windows operating system (Oriental covers Chinese, Japanese, and
Korean Windows). The Technique selection field may be truncated if you select English Windows.
Oriental Windows uses shows slightly bigger letters than English Windows, and does not support
certain symbols. For instance, the symbol "µ" may not be displayed properly in Oriental Windows.
When set to Oriental, the program will use "u" instead of "µ".
Erase ADC Calibration Coefficients
The analog-to-digital converter (ADC) calibration coefficients are stored in the instrument's non-volatile
memory. ADC calibration is carried out in the factory before the instrument is shipped. Use this
command only if you want to recalibrate the ADC yourself. To do so, simply click this button, and the
program will automatically prompt you to calibrate the ADC during the next hardware test or experiment.
Data Length (requires program restart)
The default data length is 128K. It is recommended not to use longer data lengths unless necessary.
Longer data lengths will require more computer resources, slow down your PC, and may prevent other
programs from running.
After changing this setting, please exit and restart the program; otherwise the program may crash.
If data are acquired and saved with a longer data length but read back with a shorter data length, the
program may also crash. To prevent this, if the data length has been increased, it should not be
decreased to a smaller value later. Please take this into consideration before you decide to increase the
data length.
Save retrieve data during run
This option allows data to be saved on the PC hard drive during an experimental run. In case your
experiment does not run to completion, e.g., due to external interference, interruption, or missed
communication, data can be recovered partially. This is useful for very slow experiments; hours of
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107
experimental data can be recovered.
For performance reasons, this command is not enabled by default. If a fast experiment is accidentally
interrupted, it may prove more expedient to simply re-run the experiment instead of using the Retrieve
command, which is located under the File menu.
Present Data Override Warning
If your experimental data is not saved before running a new experiment or opening an existing file on the
disk, your unsaved data will be overridden. This option will allow system to issue a warning before the
data is lost.
Save Text File As Well
By default, the program only saves binary data files, which contain extra system information (including
experimental control information). This option allows you to save your data in text format as well
whenever you save a binary data file. This is useful for exporting data to read into other software (e.g.,
spreadsheets).
Check Com port while idling
Allow the program to periodically check that a valid and available Com (serial) port number has been
assigned. If so, then "COM OK" will be displayed in the Status Bar. This will not check for a compatible
instrument connected to the Com port. In particular, "COM OK" will be displayed for any traditional serial
ports or external USB-serial converters, even if there is no instrument attached at all.
This check box is deprecated in favor of "Automatically detect Com port".
Automatically detect Com port
When this option is checked, the program will detect a compatible instrument and assign its Com port
number automatically. This requires that the instrument be powered on and connected to your computer.
Set Com Port
Press this button to assign your instrument's Com port number. This will take the "Automatically detect
Com port" setting into account.
If the Com port assignment does not succeed, the dialog will not be closed. To assign your Com port
number and close the dialog regardless of whether the change succeeds, use the OK button instead.
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4.4
CH Instruments Model 900D Series
Hardware Test command
Use this command to test the system hardware. The system will test digital and analog circuitry.
After the test, the system will display the test results in the Hardware Test Results dialog box.
The Self Test command tests the digital and analog circuitry in the instrument. This command presents
the following dialog box:
Review the Self Test results carefully. In the case of an analog test error, please repeat the test several
times to see if the error is consistent. Record the error message and contact the factory for servicing.
Digital Circuitry Test Results
Firmware version number and revision date
ROM test result (if applicable)
RAM test result (if applicable)
Potential and current offset test
If this test has been failed, an error message will be given.
Sensitivity scale test
If this test has been failed, an error message will be given. This error is usually is related to leakage
current.
Gain test
If this test has been failed, an error message will be given. There are 3 gain stages.
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Analog Test Summary
If no error has been detected, the message box will simply read “Analog circuitry test OK.” Errors
caused by the analog-to-digital converters will also be reported here.
In the case of an analog test error, please repeat the test several times to see if the error is consistent.
Record the error message and contact the factory for servicing.
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Control Menu
The Control menu offers the following commands:
Run Experiment
Pause / Resume
Stop Run
Reverse Scan
Zero Current
Zero Time
Run Status
Repetitive Runs
Multiplexer
Macro Command
Open Circuit Potential
iR Compensation
Filter Setting
Cell
Step Functions
Preconditioning
Rotating Disk Electrode
Other
Stripping Mode
SECM Probe
© 2014 CH Instruments, Inc.
Start running an experiment.
Pause or unpause an experiment.
Stop running an experiment.
Reverse potential scan direction (CV only)
Zero current
Zero time
Set certain conditions for running an experiment.
Run an experiment multiple times.
Set options for multiplexer (sold separately; hardware support required).
Execute a series of commands (cf. batch file or shell script).
Measure the open circuit potential.
Set and test iR compensation (select models only).
Set potential and current filters.
Set and control the electrochemical cell.
Generate square waveform for cleaning, etc. (select models only).
Condition working electrode before experiment.
Set rotating disk electrode control parameters (select models only).
Set miscellaneous options (select models only).
Set stripping mode and conditions.
Calibrate and control the SECM probe (900 series only).
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CH Instruments Model 900D Series
Run Experiment command
Use this command to start running your experiment.
This command can also be used to skip Quiet Time, Deposition Time or Preconditioning and go to the
next step.
Before each run, the program will first verify data link with the instrument before proceeding. The program
will also verify the values of experimental parameters; if illegal values have been entered, the command
will terminate and the program will issue an error message.
During most experiments, data can be displayed in real time. When the data acquisition speed exceeds
the data transmission rate, the results will be displayed immediately following the experiment.
Graphics can be copied to the clipboard during the run. The experiment can be halted by invoking the
Stop command.
This command has a toolbar button:
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113
Pause / Resume command
Use this command to pause and unpause your experiment.
This command is unavailable for time-based techniques, e.g., CA, CC, BE, DPA, DDPA, TPA, IMP,
IMP-t, CP, PSA.
This command has a toolbar button:
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5.3
CH Instruments Model 900D Series
Stop Run command
Use this command to stop running your experiment.
This command can also be used to stop repetitive runs or macro commands. It has a toolbar button:
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115
Reverse Scan command
Use this command to reverse the potential scan direction during a cyclic voltammetry experiment.
Each time this command is invoked, the sweep segment counter increments.
If this command is used during an experiment, certain data analysis features will be unavailable, e.g.,
peak search.
This command has no effect for other techniques. It has a toolbar button:
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5.5
CH Instruments Model 900D Series
Zero Current command
During an Amperometric i-t Curve experiment, the Zero Current command will manually bias the current
to zero, to facilitate current reading after the baseline has settled. This is particularly useful for
electrochemical detection.
This command can only be used while an Amperometric i-t Curve experiment is in progress, and it
cannot be used for other techniques. It has a toolbar button:
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117
Zero Time command
During an Amperometric i-t Curve experiment, the Zero Time command set the time to zero, throwing
away all previous data points. This command can facilitate the time reading and reduce the number of
unusable data points, and is particularly useful for electrochemical detection.
This command can only be used while an Amperometric i-t Curve experiment is in progress, and it
cannot be used for other techniques.
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5.7
CH Instruments Model 900D Series
Run Status command
This command opens the Run Status dialog box.
Use this command to adjust certain options related to the currently running experiment, including iR
compensation, automatic smoothing, purge, stir, and prerun mercury drops.
The Run Status command presents this dialog box.
Calibration Before Run
When this box is checked, the potential and current offsets will be measured and compensated before
running the experiment. Disable this option to allow the experiment to start faster.
Check Connection Before Run
When this box is checked, the program will verify that the counter and reference electrodes are
connected before running the experiment. If one of the electrodes is not connected, a warning message
will appear; proceed with the experiment at your own caution. This option can prevent accidental damage
to the working electrode due to an open loop. Disable this option to allow the experiment to start faster.
Use Open Circuit E as Init E
When this box is checked, the program will measure the open circuit potential before running the
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experiment and use this value as the initial potential.
External Trigger Run
When this box is checked, the experiment will be initiated by an external trigger signal from the Cell
Control port on the rear panel. Consult the appendix of the user manual for pin assignments.
iR Comp for Next Run
When this box is checked, iR compensation will be enabled for the next run. You may be unable to
enable iR compensation if automatic compensation has been set but the iR compensation test has not
been conducted, or if the sensitivity scale has been altered. iR compensation is not available for certain
techniques, such as TAFEL, BE, IMP, CP, and PSA. This option can also be turned on or off from the iR
Compensation command under the Control menu.
Smooth After Run
When this box is checked, automatic smoothing will be performed after the run. Certain techniques,
such as TAFEL, BE and IMP, do not allow smoothing. This option can also be turned on or off using the
Smoothing command under the DataProc menu, where the mode of smoothing can be set to least
square or Fourier transform.
Purge Between Runs
Check this box to enable purging between runs.
Stir Between Runs
Check this box to enable stirring between runs.
SMDE Drops Before Run
When using the static mercury drop electrode (SMDE), specify the number of mercury drops to be
dispensed before the experiment. Normally the system will issue a combined dispense and knock signal
before running the experiment to allow a new drop to be formed.
This parameter should be between 0-20 (default 1); if set to 0, the same drop used in the previous
experiment will be used for the next experiment. It may be useful to use more than one prerun drop if the
SMDE occasionally traps little air bubbles in the capillary and loses contact.
This option can also be varied using the Cell command under the Control menu.
E2 off During Quiet Time (if applicable)
Not applicable for your instrument series.
Abort Experiment at Level
The experiment will terminate automatically if the current or charge level reaches the specified value (or
overflows). This allows electrode over-current protection.
If "No" is selected, the experiment will end normally.
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CH Instruments Model 900D Series
If "10s Change <" is selected, the experiment will terminate automatically if the signal change after 10
seconds is less than the specified value (in Amperes for current and Volts for potential). This option is
applicable only for time-based techniques, such as CA, IT, DPA, DDPA, and TPA.
The program does not monitor the signal change during the first 10 seconds of the experiment. After
that, the program checks every time it samples. The response time is equal to the sampling interval.
After data is read, the program compare with the data point sampled 10 seconds ago and the difference
will be checked. If the difference is less than the specified value, the experiment will terminate.
Abort Quiet Time
The quiet time before data acquisition will terminate automatically if the current or charge level reaches
the specified value (or overflows). If "No" is selected, the experiment will end normally.
Current Display during Quiet Time
Specify whether the current during quiet time is displayed numerically, graphically, or not at all. The
sensitivity scale will be automatically adjusted in order to read the current properly. If "No" is selected,
the current will not be displayed during quiet time, and the sensitivity will be the same as that used in
the experiment.
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121
Repetitive Runs command
This command opens the Repetitive Run dialog box.
Use this command to run an experiment multiple times. Before each run, the program will first verify data
link with the instrument, aborting the series of runs if link fails. The program will also verify the values of
experimental parameters; if illegal values have been entered, the command will terminate and the
program will issue an error message.
The Repetitive Runs command opens this dialog box.
Number of Runs
Enter the number of runs; the parameter range is 1 - 9999.
Time Interval Between Runs
Specify the time delay between two successive runs; the parameter range is 0 - 32767. This parameter
is ignored if Prompt Before Each Run is enabled.
Prompt Before Each Run
If Manual is selected, you will have to click on a message box before each run (except the 1st run). The
instrument will wait until you respond.
If External Trigger is selected, the instrument will wait for an external trigger signal before each run. The
trigger signal is an active low signal and can be applied to Pin 13 of the Cell Control port on the rear
panel.
When Manual or External Trigger is selected, the Time Interval Between Runs parameter is ignored.
Base Filename
Click Browse or type directly in this field to specify the filename prefix (up to 5 characters). Data will be
saved after each run. The run number will be attached to the base filename, i.e., filenameN, where N is
the run number. If a base filename is not specified, a warning will be given. If you continue, the system
will run the experiments without saving any data.
Data Averaging When Done
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CH Instruments Model 900D Series
When this item is checked, the data of the repetitive runs will be averaged and saved as filename0.
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123
Multiplexer command
This command opens the Multiplexer dialog box.
Use this command to run a series of experiments using the CHI684 Multiplexer (sold separately). The
multiplexer switches four lines (working, sensing, reference, and counter for a single potentiostat,
second working, reference and counter for a bipotentiostat). You can have up to 64 cells, but only one
cell can be connected at a time. The minimum number of channels for the CHI684 is 8. The channel
increment is 8. The maximum number of channels is 64.
The Multiplexer command presents this dialog box.
Channel Selection
Click a channel to enable it and uncheck to disable. If you select a channel beyond your CHI684 channel
number, it will be ignored.
Prompt Before Each Run
If Manual is selected, you will have to click on a message box before each run (except the 1st run). The
instrument will wait until you respond.
If External Trigger is selected, the instrument will wait for an external trigger signal before each run. The
trigger signal is an active low signal and can be applied to Pin 13 of the Cell Control port on the rear
panel.
Base Filename
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CH Instruments Model 900D Series
Click Browse or type directly in this field to specify the filename prefix (up to 5 characters). Data will be
saved after each run. The run number will be attached to the base filename, i.e., filenameN, where N is
the channel number. For instance, if you set base filename as "test", and you select channels 3, 8, 23,
and 58, Run Multiplexer will run 4 experiments and save data as test3.bin, test8.bin, test23.bin, and
test58.bin. If a base filename is not specified, a warning will be given. If you continue, the system will run
the experiments without saving any data.
Before execution, the program will check for existing data files with a same base filename, issuing an
overwrite warning if found.
Immediate Channel Set
This allows you to select an arbitrary channel immediately. You can then exit the dialog box and run an
experiment for that particular channel.
Run Multiplexer
Click this button to run experiments for the selected channels using the CHI684 Multiplexer.
Experimental conditions should be set before this command is executed.
Side Note: Multiplexer-Related Macro Commands
Two Macro commands are available for the CHI684 multiplexer.
The macro comamnd "mch:##" allows you to select an individual channel.
The macro command "mchn" is used in For loops to select the channel given by the For loop counter.
Note that this macro command will run in 1,2,3,4... sequence; you cannot skip channels in a For loop.
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125
Macro Command command
This command opens the Macro Command dialog box.
Use this command to execute a series of other commands. This is analogous to batch files in Windows
or shell scripts in Unix/Linux and is much more flexible than the Repetitive Runs command.
The Macro Command command presents this dialog box.
Read
Load macro from file. The program displays the Open dialog box so you can select your file.
Save
Save macro to file for later use. The program displays the Save As dialog box so you can name your file.
Test
Test macro for syntax errors. The program will automatically do this when the macro is run; this button
is included so that you can check your macro before you are finished writing it.
Run Macro
Click this button to execute the macro. The system will verify the commands and parameter ranges of
your macro before proceeding.
Run on OK
When this box is checked, the macro will execute after you click the OK button. When this box is
unchecked, the dialog box will close when you click OK, saving your macro without running it (the old
default behavior of OK).
Macro Command Editor
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CH Instruments Model 900D Series
Type in the desired series of commands in the editor box. Each command occupies one line. The
command is case insensitive. Space will be ignored. If a parameter is required following the command, a
colon ":" or a equal sign "=" is used to separate the command and parameter.
Any text following a semicolon ";" or pound symbol "#" on a line will be ignored (inline comments).
Run Macro Files from Command Line
chi660e.exe /runmacro:"C:\CHI\test.mcr"
Legal Commands (common)
Command
Parameter
Explanation
tech
string
select an electrochemical technique
folder
string
specify where to save files: e.g., c:\chi\test
run
run experiment
save
string
save data to file; when used in for…next loop,
filename will be truncated to 5 letters and loop
number (1-999) will be added to filename
tsave
string
save data as text file
fileoverride
allow file override without warning
macrotest
check macro without execution
end
end of macro; lines below will be ignored
beep
sound notification
for
1 - 999
next
for…next loop; only one layer is allowed
end of for…next loop
delay
1 - 32000
delay between commands
purge
1 - 32000
purge for specified time
stir
1 - 32000
stir for specified time
trigon
turn on trigger before run
trigoff
turn on trigger before run
knockon
turn on drop knocker; also used to send trigger
pulse to external device before run
knockoff
turn off drop knocker; no pulse before run
qcmon
QCM mode on
qcmoff
QCM mode off
auxon
turn on auxiliary signal recording channel
auxoff
turn off auxiliary signal recording channel
cellon
cell on between runs
celloff
cell off between runs
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Control Menu
dummyon
enable internal dummy cell
dummyoff
disable internal dummy cell
rdeon
turn on RDE
rdeoff
turn off RDE
rdedepositionon
RDE on during deposition
rdedepositionoff
RDE off during deposition
rdequieton
RDE on during quiet time
rdequietoff
RDE off during quiet time
rderunon
RDE on during run
rderunoff
RDE off during run
rdebetweenrunon
RDE on between runs
rdebetweenrunoff
RDE off between runs
rpm
0 - 10000
RDE rotation rate in rpm
rpmincr
0 - 1000
RDE rotation rate increment in rpm
rpmsqrt
0 - 100
square root of rotation rate
rpmsqrtincr
0 - 10
square root of rotation rate increment
aflt
automatic filter setting
flt1
0 - 8
potential filter: 0=none, 1=150KHz, 2=15KHz, …
flt2
0 - 7
i/V converter: 0=none, 1=32kHz, 2=3.2kHz, …
flt3
0 - 8
signal filter: 0=none, 1=150KHz, 2=15KHz, …
flt4
0 - 7
2nd channel i/V: 0=none, 1=32kHz, 2=3.2kHz, …
flt5
0 - 8
2nd channel signal filter: 0=none, 1=150KHz, …
mch
1 - 64
select multiplexer channel
mchn
multi. channel selection according to for/next loop
ei
-10 - +10
initial potential
eh
-10 - +10
high limit of potential in CV, CA, CP
el
-10 - +10
low limit of potential in CV, CA, CP
ef
-10 - +10
final potential for single sweep tech and PSA
eio
use open circuit potential (OCP) as init E;
disabled after new init E is specified by ei
eho
use OCP as high E; disabled by eh command
elo
use OCP as low E; disabled by el command
efo
use OCP as final E; disabled by ef command
eioei
-10 - +10
use OCP + this value as init E; disabled by ei
eioef
-10 - +10
use OCP + this value as final E; disabled by ei
eiocenter
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use OCP as center potential; shifts high and low
E limits on both sides of OCP
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CH Instruments Model 900D Series
eiincr
-1 - +1
increment init E in for...next loop; should be reset
to zero after loop
efincr
-1 - +1
increment final E in for...next loop; should be
reset to zero after loop
ehincr
-1 - +1
increment high E in for...next loop; should be
reset to zero after loop
elincr
-1 - +1
increment low E in for...next loop; should be reset
to zero after loop
fullcycleon
CV full cycle on
fullcycleoff
CV full cycle off
efon
Final E on
efoff
Final E off
sens
1e-12 - .1
sensitivity scale
sens2
1e-12 - .1
sensitivity for 2nd working electrode if applicable
autosens
automatic sensitivity if applicable
qt
0 - 100000
quiescent time before run if applicable
ht
0 - 100000
hold time at final E if applicable
smodeon
turn on stripping mode
smodeoff
turn off stripping mode
depeon
turn on deposition potential in stripping mode
depeoff
turn off deposition potential in stripping mode
depe
-10 - +10
deposition potential
dept
1 - 100000
deposition time in seconds
quieteon
turn on quiet potential in stripping mode
quieteoff
turn off quiet potential in stripping mode
quiete
-10 - +10
quiescent potential in stripping mode
pcon
turn on preconditioning
pcoff
turn off preconditioning
pcon2
turn on preconditioning for channel 2
pcoff2
turn off preconditioning for channel 2
initeon
return to initial potential after run
initeoff
remain at final potential after run
pce1
-10 - +10
potential for 1st stage of preconditioning
pce2
-10 - +10
potential for 2nd stage of preconditioning
pce3
-10 - +10
potential for 3rd stage of preconditioning
pct1
0 - 6400
time for 1st stage of preconditioning
pct2
0 - 6400
time for 2nd stage of preconditioning
pct3
0 - 6400
time for 3rd stage of preconditioning
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Control Menu
noabort
do not abort experiment during run
abortov
abort experiment if current overflow
abortigt
0 - 2
abort experiment if current > specified value
abortilt
0 - 2
abort experiment if current < specified value
abortq
0 - 100000
abort experiment if charge > specified value
abort10s
0 - 1
abort experiment if signal change in 10 seconds
is less than specified value
abortchgt
1 - 3600
revise abort10s to specified time interval
bce1a
-10 - +10
Baseline Correction (BC; a.k.a. baseline fitting
and subtraction): 1st peak foot "from" potential
bce1b
-10 - +10
BC: 1st peak foot "to" potential
bce2a
-10 - +10
BC: 2nd peak foot "from" potential
bce2b
-10 - +10
BC: 2nd peak foot "to" potential
bce3a
-10 - +10
BC: 3rd peak foot "from" potential
bce3b
-10 - +10
BC: 3rd peak foot "to" potential
bce4a
-10 - +10
BC: 4th peak foot "from" potential
bce4b
-10 - +10
BC: 4th peak foot "to" potential
bce5a
-10 - +10
BC: 5th peak foot "from" potential
bce5b
-10 - +10
BC: 5th peak foot "to" potential
bcorder
1 - 19
BC polynomial order
bcalgor
0 - 1
BC algorithm: 0=orthogonal, 1=least squares
note
string
specify note field
header
string
specify header field in plot
forcequit
yesiamsure
terminate program (use at your own risk!)
Legal Commands (bipotentiostat only)
Command
Parameter
Explanation
e2on
turn on 2nd working electrode (no data recording)
e2off
turn off 2nd working electrode
i2on
turn on 2nd working electrode and record data
i2off
turn off 2nd working electrode
e2
-10 - +10
initial potential for channel 2
e2scan
2nd channel scan or step w/ primary channel
e2d
constant potential difference between 2nd and
primary channel during potential scan or step
e2dscan
enable 2nd channel potential scan w/ primary
channel but keep constant potential difference
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CH Instruments Model 900D Series
Legal Commands (multipotentiostat only)
Command
Parameter
Explanation
ei
-10 - +10
initial potential for channel 1
e2
-10 - +10
potential for channel 2
e3
-10 - +10
potential for channel 3
e4
-10 - +10
potential for channel 4
e5
-10 - +10
potential for channel 5
e6
-10 - +10
potential for channel 6
e7
-10 - +10
potential for channel 7
e8
-10 - +10
potential for channel 8
sens
1e-9 - 1e-3
sensitivity scale for channel 1
sens2
1e-9 - 1e-3
sensitivity scale for channel 2
sens3
1e-9 - 1e-3
sensitivity scale for channel 3
sens4
1e-9 - 1e-3
sensitivity scale for channel 4
sens5
1e-9 - 1e-3
sensitivity scale for channel 5
sens6
1e-9 - 1e-3
sensitivity scale for channel 6
sens7
1e-9 - 1e-3
sensitivity scale for channel 7
sens8
1e-9 - 1e-3
sensitivity scale for channel 8
e1on
turn on channel 1
e2on
turn on channel 2
e3on
turn on channel 3
e4on
turn on channel 4
e5on
turn on channel 5
e6on
turn on channel 6
e7on
turn on channel 7
e8on
turn on channel 8
e1off
turn off channel 1
e2off
turn off channel 2
e3off
turn off channel 3
e4off
turn off channel 4
e5off
turn off channel 5
e6off
turn off channel 6
e7off
turn off channel 7
e8off
turn off channel 8
e2scan
scan or step channel 2 with primary channel
e3scan
scan or step channel 3 with primary channel
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Control Menu
e4scan
scan or step channel 4 with primary channel
e5scan
scan or step channel 5 with primary channel
e6scan
scan or step channel 6 with primary channel
e7scan
scan or step channel 7 with primary channel
e8scan
scan or step channel 8 with primary channel
eiincr
-1 - +1
increment e1 in for...next loop; should be reset to
zero after loop
e2incr
-1 - +1
increment e2 in for loop; should be reset to 0 after
e3incr
-1 - +1
increment e3 in for loop; should be reset to 0 after
e4incr
-1 - +1
increment e4 in for loop; should be reset to 0 after
e5incr
-1 - +1
increment e5 in for loop; should be reset to 0 after
e6incr
-1 - +1
increment e6 in for loop; should be reset to 0 after
e7incr
-1 - +1
increment e7 in for loop; should be reset to 0 after
e8incr
-1 - +1
increment e8 in for loop; should be reset to 0 after
sequential
sequential measurements
simultaneous
simultaneous measurements
indcell
independent cell
onecell
single cell with common reference and counter
131
For a complete list of technique-specific macro commands, please consult your .chm or .hlp help file.
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5.11
CH Instruments Model 900D Series
Open Circuit Potential command
Use this command to measure the open circuit potential.
The open circuit potential is the potential between the working electrode and reference electrode while no
current is flowing through the cell. This is an important parameter. It gives you information about the
initial conditions before you start the experiment. You can then figure out if the compound under study is
oxidizable or reducible.
After the measurement, the program will display the open circuit potential value through the Open Circuit
Potential dialog box.
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133
iR Compensation command
This command opens the iR Compensation dialog box.
Use this command to test the solution resistance and cell time constant, as well as switch between
automatic or manual iR compensation.
This command has a toolbar button:
The iR Compensation command presents this dialog box.
iR Comp Test Results
Click the Test button to execute the solution resistance and cell time constant test. The result will be
reported here.
After that the program will test stability by gradually increasing the compensation level until the desired
compensation level is reached or the system is no longer stable. The allowed compensation level and
uncompensated resistance will be displayed. The uncompensated resistance is calculated from the
measured resistance and the allowed compensation level.
Please note that the maximum allowed resistance and compensation may be limited to the feedback
resistor of the i/E converter.
iR Comp Test
Before starting the iR compensation test, these test parameters must be specified correctly.
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CH Instruments Model 900D Series
Test E is the test potential at which no electrochemical reaction will occur. When the system is
performing the test, it applies a potential step relative to the test potential. The test is passed only if the
electrochemical cell can be considered equivalent to a solution resistance in series with a double layer
capacitor. The allowed range of the Test E parameter is -10V to +10V.
Step Amplitude refers to the magnitude of the applied potential step. The larger the amplitude, the higher
the signal-to-noise ratio. However, too large of an amplitude may cause faradaic current to flow. A step
amplitude of 0.05V is recommended. The allowed range of the Step Amplitude parameter is 0.01V to
0.25 V.
The compensation level (Comp Level) is the percentage of resistance you want to compensate based on
the measured solution resistance. The allowed range of this parameter is 0% to 200% (default 100%).
Overshoot level is the criterion of the stability test. As the amount of positive feedback increases, the
system might become unstable. Before the potentiostat starts to oscillate, an overshoot in current in
response to the potential pulse will be observed. The higher the allowed overshoot level, the higher the
possible compensation level, but the worse the system stability. The range of this parameter is 0 100%. The default level is 2%.
Click the Test button to perform the solution resistance and stability test. The result will be reported in
the iR Comp Test Results Box.
For more details about iR compensation, please refer to “Intelligent, Automatic Compensation of Solution
Resistance”, P. He, and L. R. Faulkner, Anal. Chem., 58, 517-523 (1986).
iR Compensation for Next Run
When this box is checked, iR compensation will be enabled for the next run. You may be unable to
enable iR compensation if automatic compensation has been set but the iR compensation test has not
been conducted, or if the sensitivity scale has been altered. This option can also be turned on or off from
the Run Status command under the Control menu.
iR Comp Enable
If the "Once" option is selected, iR compensation will be applied only to the next run and subsequently
disabled. If you want the same compensation conditions to be applied to consecutive runs, select the
"Always" option.
iR Comp Mode
Specify the mode of iR compensation. Automatic iR compensation will be based on the iR
compensation test results. Manual iR compensation uses the resistance value you specify in the
Resistance field below.
Manual Compensation Resistance
Specify the resistance value that you want system to compensate; this value is used only for manual iR
compensation. Choose this value with care; if the compensation level is close to or exceeds the actual
solution resistance, the potentiostat will oscillate. Please also notice that the maximum allowed
resistance compensation may be limited to the feedback resistor of the i/E converter.
This parameter will be ignored if automatic iR compensation is selected.
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Filter Setting command
This command opens a Filter Selection dialog box. Use this command to set potential and current
filters.
The potential filter is used to filter the potential waveforms. It is a second-order Bessel low-pass filter and
can be used to filter out transient components. The potential filter can be used, for instance, to convert a
staircase ramp to a linear sweep.
A capacitor can be connected to the feedback resistor of the i/E converter to form a low-pass RC filter.
This can remove the high-frequency noise at the first hand.
The signal filter is applied before the gain stage. It is a second-order Bessel low-pass filter.
These filters are useful for reducing the amount of noise during measurements.
Click the Help button in the resulting dialog box for more information.
This command has a toolbar button:
The Filter Setting command presents this dialog box.
The "2nd" columns apply to dual-channel measurements.
If you are unsure what settings to choose, please select "Automatic".
Potential Filter
The grayed-out box displays the actual potential filter setting. Choose the potential filter cutoff frequency
from the list.
The potential filter is a 2nd order Bessel filter used to shape the waveforms. The appropriate setting for
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this filter should take the type and time scale of the experiment into account. For instance, the
Automatic setting will filter out high frequency components to avoid aliasing in AC impedance
measurements, whereas in linear sweep voltammetry it will convert the staircase ramp to a true linear
potential sweep.
i/E Conv Filter
The grayed-out box displays the actual current-to-voltage converter filter setting. Choose the i/E
converter filter cutoff frequency from the list.
The i/E converter filter is an RC filter in conjunction with the current-to-voltage (i/E) converter. The
appropriate setting for this filter should take the type and time scale of the experiment into account.
In certain cases, some cutoff frequencies cannot be selected. This is because for a given sensitivity
scale, the feedback resistor of i/E converter is fixed, and when this is combined with the RC filter, it may
be impossible to reach certain cutoff frequencies. For instance, a low (high) sensitivity scale could
preclude the selection of a relatively low (high) cutoff frequency. You may be able to select the desired
cutoff frequency by altering the sensitivity scale.
Signal Filter
The grayed-out box displays the actual signal filter setting. Choose the signal filter cutoff frequency from
the list. The signal filter is a 2nd order Bessel filter. The appropriate setting for this filter should take the
type and time scale of the experiment into account.
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Cell command
This command opens a Cell Control dialog box.
Use this command to control purge, stir, and electrochemical cleaning settings. You can also set the
signal level of the stir line, mercury drop collection, prerun drops, and stabilizing capacitor.
Click the Help button of the resulting dialog box for more information.
This command has a toolbar button:
The Cell command presents this dialog box.
Control Level of Stir Line
The stir line control signal can be specified as active high (BAS) or active low (PAR).
Immediate Stir
Specify the immediate stir time (from 1 - 32767). Click the Stir button to activate immediate stirring.
Immediate Purge
Specify the immediate purge time (from 1 - 32767). Click the Purge button to activate immediate purging.
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Immediate Cell On
Specify the cell potential (from -10 to +10) and the cell on time (from 1 to 32767). Click the Cell On
button to poise the electrode at this potential for the specified amount of time.
SMDE Drops Before Run
When using the static mercury drop electrode (SMDE), specify the number of mercury drops to be
dispensed before the experiment. Normally the system will issue a combined dispense and knock signal
before running the experiment to allow a new drop to be formed.
This parameter should be between 0-20 (default 1); if set to 0, the same drop used in the previous
experiment will be used for the next experiment. It may be useful to use more than one prerun drop if the
SMDE occasionally traps little air bubbles in the capillary and loses contact.
Stabilizing Capacitor
There is a 0.1 F stabilizing capacitor that can be connected between the counter and reference
electrodes. This capacitor can stabilize the potentiostat but slows the system down somewhat. This is
particularly useful when the double layer capacitance of the working electrode is large, such as in bulk
electrolysis, or when a high degree of iR compensation is required.
When the Automatic Setting box is checked (default), the system will manage the stabilizing capacitor
without user intervention; uncheck this box to manage the stabilizing capacitor manually with the radio
buttons in this section.
Mercury Drop Collection
This useful option allows you to collect and weigh mercury drops. Specify the number of drops you want
to collect (from 1 to 1000) and the time interval between drops (from 0.5 to 10), and click the Collect
button to activate the collection process.
4 Electrodes
Check this box to set the potentiostat in 4-electrode mode.
The 4th electrode is used for sensing the voltage drop due to the contact resistance of the electrode clip,
connector, relay, and circuit board traces. The contact resistance can be about 0.2 - 0.3 ohm and can
cause a 50 - 75 mV voltage drop if the current is 250 mA, making low impedance cell measurements
impossible (e.g., battery). With the addition of the 4th electrode, the effect of contact resistance can be
eliminated, and low impedance cells can be readily measured.
The 4th electrode can also be used for liquid/liquid interface measurements. In the first liquid phase, the
red clip is connected to the counter electrode and the white clip is connected to the reference electrode.
In the second liquid phase, the green clip is connected to the counter electrode and the black clip is
connected to the reference electrode.
You should turn the 4th electrode off if you do not use a 4-electrode configuration. Otherwise the
potential will be out of control if the sensing electrode is left unconnected, which could damage the
electrodes.
Purge Between Runs
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Check this box to enable purging between runs. This option can also be turned on or off using the Run
Status command under the Control menu.
Stir Between Runs
Check this box to enable stirring between runs. This option can also be turned on or off using the Run
Status command under the Control menu.
Stir and Purge Simultaneously
Check this box to stir and purge at the same time.
Test with Internal Dummy Cell
Check this box to run the experiment with the instrument's internal dummy cell (a built-in 1K ohm
resistor) instead of an external cell, which can be useful for testing the instrument.
Cell On Between Runs
Normally, the cell will be turned on only during an experiment and turned off after the experiment ends.
Check this box to keep the cell connected after a run. Be careful when this option is enabled.
Connecting or disconnecting the cell in an improper sequence can damage the electrodes when the cell
is on. You should connect the reference and counter electrodes first. When disconnecting, disconnect
the working electrode first.
Return to Initial E after Run
Check this box to set the potential back to the Initial E value after a run; otherwise, the potential will
remain at the final value of the previous run. It only makes sense to enable this option if Cell On Between
Runs is also checked.
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Step Functions command
This command opens the Step Functions dialog box.
Use this command to generate a continuous square waveform for electrode conditioning, cleaning, or
other purposes. No data will be collected and displayed.
The Step Functions command presents this dialog box.
Parameter
Range
Description
Start E (V)
-10 - +10
Starting potential
Duration (s)
0 - 100000
Duration at Start E
Step E1 (V) / i1 (A)
-10 - +10
First step potential
Step Time 1 (s)
.0001 - 100000
Duration of each step
Step E2 (V) / i2 (A)
-10 - +10
Second step potential
Step Time 2 (s)
.0001 - 100000
Duration of each step
Step Segments
1 - 2000000000
Step segments; each segment is a half cycle
Galvanostatic Mode
Check or Uncheck
Galvanostatic or potentiostatic (unchecked) mode
Notes
1. The potential range between Start E, Step E1, and Step E2 should be less than 13.1 V.
2. If Duration is less than 0.001 sec, the Start E potential will be ignored.
3. The steps are applied in the sequence of Step E1, Step E2, Step E1, Step E2, ... Thus, the final
potential will be Step E1 for an odd number of segments and Step E2 for an even number.
Run
Click the Run button to activate the step function generator. No data will be collected and displayed.
A status box will be displayed showing the number of steps completed, the remaining steps and the
remaining time. Cancel this function by pressing the Stop pushbutton.
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CH Instruments Model 900D Series
Preconditioning command
This dialog box opens the Preconditioning before Run dialog box. Use this command to condition the
working electrode before running an experiment. This can be useful for cleaning the electrode among
other purposes. Preconditioning occurs before the deposition or quiet time.
The Precondition command presents this dialog box.
The working electrode will be conditioned with up to three potential steps.
Enable Preconditioning
Uncheck this box to disable proconditioning, which occurs before the deposition or quiet time.
Potential
The parameter range is from -10 to 10.
Time
The parameter range is from 0 to 6400. Set to 0 to skip a given step. If a nonzero value less than 1 msec
is specified, the time control may not be accurate.
Stir On
Check this box to enable stirring during preconditioning.
Purge On
Check this box to enable purge during preconditioning.
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CH Instruments Model 900D Series
Rotating Disk Electrode command
This command, available only in select models, opens the Rotating Disk Electrode Control dialog box.
Use this command to specify the rotation rate of the rotating disk electrode. You can also turn the
rotator on and off in certain cases.
The Rotating Disk Electrode command presents this dialog box.
Rotation Speed (rpm)
Specify the speed of the rotating disk electrode from 0 to 10000 rpm. There are banana jacks on the rear
panel of the instrument that will output 0 to 10 V corresponding to these speeds.
Rotate during Deposition Time
Check this box to turn the rotator on during deposition time in stripping analysis. This option can also be
found in the Run Status command under the Control menu.
Rotate during Quiet Time
Check this box to turn the rotator on during quiet time. This option can also be found in the Run Status
command under the Control menu.
Rotate during Run
Check this box to turn the rotator on during the experiment. This option can also be found in the Run
Status command under the Control menu.
Rotate between Runs
Check this item to turn the rotator on between experiments. This option can also be found in the Run
Status command under the Control menu.
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Other command
This command opens the Other Controls dialog box. Use this command to control the cooling fan and
working electrode static discharge protection.
The Other command presents this dialog box.
Fan Control
The instrument as all electronics will generate heat. Most components consume minimal power, but the
voltage regulators, buffer amplifiers, and some other amplifiers may grow warm, particularly when higher
currents are passing through the cell. Turning the fan on will help help to dissipate this heat and cool the
instrument. However, the fan will also generate mechanical noise and electrical interference.
When current sensitivity is set to 0.01 A/V or lower or if automatic sensitivity is employed, the fan will be
turned on automatically.
Check the appropriate box to turn the fan on during or between experiments.
WE Static Discharge Protection
The working electrode input amplifier is automatically protected from static discharge protection.
However, the protection circuit generates extra leakage current at the input stage. This leakage current
is normally less than 50 pA and is therefore not noticeable if the current is at nanoamperes or higher.
For low current measurements, you may want to turn off discharge protection when the sensitivity is
high. However, if you are doing electrochemical detection for electrophoresis, it is advisable for the
protection circuit to be connected at all times to prevent possible high voltage feedthrough.
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CH Instruments Model 900D Series
Stripping Mode command
This command opens the Stripping Control dialog box.
Use this command to enable/disable the stripping mode and specify deposition conditions. This
command is only available for the following techniques: LSV, SCV, DPV, NPV, SWV, ACV, SHACV. It
is not available in polarographic mode.
The Stripping Control command presents this dialog box.
Stripping Mode Enabled
Check this box to enable stripping mode, inserting a deposition step before the quiet time step
preceding the experiment. The deposition potential and time can be specified in this dialog box.
After the deposition period and before quiet time, the potential will be set back to its initial value. The
potential scan during the stripping step will start from this value.
Purge During Deposition
When this box is checked, the system will purge the solution during the deposition period.
Stir During Deposition
When this box is checked, the system will stir the solution during the deposition period.
Deposition Potential
Specify whether the initial potential or the value specified in the Deposition E field is applied during the
deposition period.
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Quiet Potential
Specify whether the initial potential or the value specified in the Quiet E field is applied during the
quiescent period.
Deposition E
Specify the value of the potential to be applied during the deposition period if the Deposition E option is
selected under Deposition Potential; this value is ignored if Initial E is selected instead.
Deposition Time
Specify the deposition time from 0 to 100000.
Quiet E
Specify the value of the potential to be applied during the quiescent period if the Quiet E option is
selected under Quiet Potential; this value is ignored if Initial E is selected instead.
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CH Instruments Model 900D Series
SECM Probe command
This command opens the SECM Probe Control dialog box.
Use this command to control the SECM probe position. You can calibrate the probe movement distance
or move the probe directly. Current and distances in absolute and relative coordinates will be displayed.
The SECM Probe command presents this dialog box.
Stage Reset
Execute this command when the instrument is first used or if the positions of the stepper stage are lost.
Before doing so, ensure that no tip is present in the tip holder; otherwise the motor move will cause the
tip to be broken.
Clicking on the Reset button will move the stage to its home position, which is stored in memory, and
then move it to the center position. After clicking on the Reset button, please wait for the operation to be
completed.
The stage position will be remembered even after the motor controller is powered off.
Stepper Stage Moving Speed
When this value is below 32 um/sec, setting resolution will be 1 nm. As moving speed increases, setting
resolution and accuracy will worsen, i.e., there is a tradeoff between speed and setting resolution. When
the Max Speed box is checked, the motor will move at maximum rate with relatively low setting
resolution. Please keep in mind that the stage may vibrate slightly when the moving speed is high. It is
recommended to raise the tip at fast speeds to prevent the tip from touching the sample surface due to
stage vibration.
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Stepper Stage Position Set and Relocate
Up to four positions can be defined by the user for quickly changing the stage position. Click the
corresponding Set button to memorize the current position as one of these points; click the Goto button
to move the stepper stage to the preset point.
Stepper Stage Position
The stepper motor position is continuously updated while this dialog box is open. Click the Zero button
to re-zero the relative position of the corresponding axis at any time. Click the Move button of the
corresponding axis to move the stepper motor to the specified position in absolute or relative
coordinates. If the requested move hits the zero or full range limit, a warning will be issued.
You can also use the scroll bar to move the stepper motor. Every click on the left or right arrow on the
scroll bar will move 1/100 of the full scale. If you click and hold down the left or right arrow, after finishing
the last move, the system will move in the requested direction until you release the mouse button. This
is useful for moving the stage while watching the position.
Piezo Stage Calibration
The Piezo block used in the Model CHI920D needs to calibrate its motor before the first measurement.
Calibration is performed using the stepper motor because its travel distance is known.
Before calibration, place four plastic washers on top of four stainless steel columns and underneath the
rectangular stainless steel plate of the cell/sample holder. Use four nylon screws to mount the
rectangular plate to four stainless steel columns. This is because during calibration, a voltage will be
applied to the metal plate (through counter and reference electrode clips). The rectangular plate must be
totally isolated from the positioner base, which is grounded. Four plastic washers and four nylon screws
are provided when the instrument is shipped. After the initial calibration, please save them for future use
in case calibration is needed again.
Insert the stainless steel pin with 10K ohm resistor (also shipped with the instrument) into the probe
holder. Then position the metal pin so that it is close to the base metal plate of the cell/sample holder.
Please see the figure below for an illustration of the pin position. The small circle indicates one of the
small holes around the center round opening of the base metal plate. For X and Y calibration, the sharp
pin end should be moved below the metal plate surface. For X calibration, the pin will move to the right
and use the wall of the hole to make electrical contact. For Y calibration, the pin will move to the front
and use the wall of the hole to make electrical contact. For Z calibration, the pin should be placed
slightly above the base metal plate. The pin will move down and use the base metal plate to make
electrical contact.
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Relative position of m etal pin and base m etal plate for piezo calibration.
Connect the working electrode clip (green) to the resistor attached to the metal pin. Connect the counter
(red) and reference (white) clips to the metal base. This configuration will allow current to flow when the
pin contacts the base metal plate.
During calibration, the motor will move in the negative direction first. The positive directions for X, Y, and
Z are right, front, and down, respectively. The piezo is fully extended. The stepper motor then moves in
the positive direction until the pin touches the base metal plate, allowing a current to flow. This stepper
motor position is saved as point 1. The piezo is then fully retracted. The stepper motor moves further in
the positive direction until the tip touches the base metal plate again. This stepper motor position is
saved as point 2. The distance between point 1 and point 2 is the full scale distance the piezo can travel.
Typically there might be a few percent deviation in calibration. It is recommend to calibrate several times
to verify that the results are reasonably repeatable. Any observed error is probably due to variations in
the metal contact position caused by the roughness of the base metal plate and the metal pin.
Please save the metal pin, plastic washers, and nylon screws for future calibration use. You may want
to check if the piezo behavior changes over time (say months or years later).
Piezo Stage Position
The probe position is continuously updated while this dialog box is open. Click the Zero button to re-zero
the relative position of the corresponding axis at any time. Click the Move button of the corresponding
axis to move the piezo to the specified position in absolute or relative coordinates. If the requested move
hits the zero or full range limit, a warning will be issued. The tip will stop at zero or full range.
You can also use the scroll bar to move the piezo. Every click on the left or right arrow on the scroll bar
will move 1/100 of the full scale.
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Graphics Menu
Chapter 6
Graphics Menu
The Graphics menu offers the following commands:
Present Data Plot
Overlay Plots
Add Data to Overlay
Replot Overlay
Plot current data graphically.
Plot multiple data sets in a single graph.
Add data sets to existing overlay plot.
Show most recent overlay plot.
Parallel Plots
Add Data to Parallel
Replot Parallel
Plot multiple data sets in side by side graphs.
Add data sets to existing parallel plots.
Show most recent parallel plots.
Zoom In
Manual Results
Peak Definition
X-Y Plot
Peak Parameter Plot
Semilog Plot
Special Plots
Graph Options
Color and Legend
Font
Copy to Clipboard
Magnify graph region.
Report results manually.
Define peak or wave parameters.
Input custom data for plotting
Plot peak current or potential versus scan rate.
Generate current-potential semilog plot.
Generate special plots.
Set graph options.
Set color and legend options.
Set graph font options.
Copy graph to clipboard.
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Present Data Plot command
Use this command to plot the currently active data.
You can rescale the X or Y axis by hovering over it, changing the mouse cursor to a double-headed
arrow. Left-click and drag to rescale the axis. This provides a convenient way to zoom out further than
the default scale and can be particularly useful for overlay plots when some data files go off the charts.
Double-clicking on an axis opens the Axis Options dialog box.
Double-clicking elsewhere in the plot area opens the Insert Text dialog box.
Other settings are available under the Graph Option, Color and Legend, and Font commands.
When data is saved to file, the display format is also saved, and is recovered when the file is loaded.
This is also true for Overlay Plots, Parallel Plots, and Print Multiple Files.
This command is disabled if there is no currently active data.
Its toolbar button is:
Double-clicking on a graph axis will open this dialog box.
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Many settings listed here can also be set using the Graph Options, Color and Legend, and Font
commands. The options unique to this dialog box are:
Axis Label Expression
The format of axis values can be selected as Scientific (e.g., 1e-6A) or Engineering (e.g., 1 A).
Warning: if you are using Oriental Windows (such as Chinese, Japanese, Korean), the "micro" symbol
will not appear properly, you need to adjust the Windows setting using System command under the
Setup menu. The “micro” symbol will then be expressed as "u".
Long/Short
These options allow you to customize long (major) and short (minor) ticks. You should freeze the axis
scale when adjusing these settings manually.
Double-clicking on a graph opens this dialog box.
The entered text will be saved with the data when you save the data file. The following options allow you
to type and format text in the data graphics field:
Text
Enter the text to be displayed. If you clear an existing Text field, text will be removed from the plot upon
exiting the dialog box.
Erase
Clear the text field.
X and Y
Change the position of the text: X and Y give the precise coordinates of the upper-left corner of the first
letter. The initial values indicate where you double-clicked.
Rotation
Rotate the text clockwise by an angle between 0 and 360 degrees.
Font
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Click the Change button to specify the style, size, color, and font of the inserted text. This setting will be
applied to all text inserted in the current plot.
Text Display Enabled
Uncheck this option to hide all text messages (the messages will not be deleted).
Default
Set the current font as the default for all data files.
Monochrome
Set the text color to black.
Depending on the active technique, data can be displayed in various formats:
Tech.
CV
TAFEL
CA
CC
SWV
ACV
PSACV
BE
IMP
Data Display Formats
sweep segment
log current ~ potential
current ~ potential
current density ~ potential
i~t
i ~ t-1/2
Q~t
Q ~ t1/2
forward current
reverse current
forward and reverse current
difference of forward and reverse current
sum of forward and reverse current
forward, reverse, and summation current
forward, reverse, and difference current
absolute current
phase selective current
resistance
capacitance
absolute current
phase selective current
resistance
capacitance
charge ~ time
current ~ time
current ~ log(time)
Bode: log Z ~ log (freq)
Bode: phase ~ log (freq)
Bode: log Z" & Z' ~ log (freq)
Bode: log Y ~ log (freq)
Nyquist: Z" ~ Z'
Admittance: Y" ~ Y'
Warburg: Z" & Z' ~ w-1/2
Z' ~ w Z"
Z' ~ Z"/w
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Graphics Menu
cot (phase) ~ w1/2
IMP-t/IMP-E log Z ~ t or E
phase ~ t or E
Z ~ t or E
Z' ~ t or E
Z" ~ t or E
Z' & Z" ~ t or E
log (Z' & Z") ~ t or E
log Y ~ t or E
Y ~ t or E
Y' ~ t or E
Y" ~ t or E
Y' & Y" ~ t or E
log (Y' & Y") ~ t or E
IMP-E
Rs ~ E
Cs ~ E
Rp ~ E
Cp ~ E
Mott-Schottky: 1 / (Cs×Cs) ~ E
Mott-Schottky: 1 / (Cp×Cp) ~ E
CP, PSA
potential ~ time
dE/dt ~ time
dt/dE ~ potential
Potential ~ charge
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Overlay Plots command
Use this command to plot multiple sets of data in a single graph. This is particularly useful for data
comparison. A multi-colored legend will be automatically generated from the data filenames. To view a
saved overlay plot, use the Replot Overlay command.
This command presents the following dialog box:
Select the data files you want to overlay with the currently active data. Multiple files can be selected. To
select multiple files, point the mouse cursor to the filename you want to select and click the left mouse
button while holding the Ctrl key down to select files one at a time.
This command allows you select multiple files in the same directory. In order to overlay data files located
in a different directory or drive, use the Add Data to Overlay command.
The plot will be automatically scaled to fit the currently active data. If both X and Y values fall into the
plot scale, the data point will be plotted.
The Graph Option, Color and Legend, and Font commands allow you customize your overlay plot.
This command does not check the type of data, and it is up to the user to ensure the meaningfulness of
the overlay plot.
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Add Data to Overlay command
This command complements the Overlay Plots command, allowing you to add more data to an existing
overlay plot. This allows you to overlay data files from multiple directories or drives.
This command presents the following dialog box:
Multiple files can be selected. To select multiple files, point the mouse cursor to the filename you want
to select and click the left mouse button while holding the Ctrl key down to select files one at a time.
The plot will be automatically scaled to fit the currently active data. If both X and Y values fall into the
plot scale, the data point will be plotted.
The Graph Option, Color and Legend, and Font commands allow you customize your overlay plot.
This command does not check the type of data, and it is up to the user to ensure the meaningfulness of
the overlay plot. It is disabled if there is no currently active data, or if the current plot is not an overlay
plot.
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CH Instruments Model 900D Series
Replot Overlay command
Use this command to display the most recent Overlay plot. This is useful after clicking the Present Data
Plot button or when loading plots from file.
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Manage Overlay command
Use this command to open the Manage Files dialog box. This will allow you to add, reorder, and remove
files from a multi-file plot.
The Manage Overlay or Manage Parallel command presents this dialog box.
This dialog box displays a list of all files being plotted with the current file. As in older versions of the
program, the current file is always the first plot, so it cannot be moved or removed. Click OK to confirm
all changes.
Add
Clicking this button has the same effect as the Add Data to Overlay or Add Data to Parallel command.
Move Up / Down
Select multiple files by holding down Ctrl or Shift key and left-clicking. You can then to move your
selection up or down in the list by clicking the appropriate Move button. The current file is always the
first plot, so you will not be able to move your selection above it.
Remove
Select file(s) as when using Move Up / Down. Once you click Remove, these files will be removed from
your plot.
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CH Instruments Model 900D Series
Parallel Plots command
Use this command to plot multiple sets of data side by side. This is particularly useful to view data
obtained with different techniques and for data comparison. To view a saved parallel plot, use the Replot
Parallel command.
This command presents the following dialog box:
Select the data files you want to plot alongside the currently active data. Multiple files can be selected.
To select multiple files, point the mouse cursor to the filename you want to select and click the left
mouse button while holding the Ctrl key down to select files one at a time.
This command allows you select multiple files in the same directory. In order to plot data files located in
a different directory or drive, use the Add Data to Parallel command.
Each plot will be automatically scaled to fit its individual data, unless the scale is frozen using the Graph
Option command. In this case, all plots will have the same frozen scale.
The Graph Option, Color and Legend, and Font commands allow you customize your overlay plot.
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Add Data to Parallel command
This command complements the Parallel Plots command, allowing you to add more data to an existing
parallel plot. This allows you to plot data files from multiple directories or drives, as well as control the
sequence of the data in the plots.
This command presents the following dialog box:
Multiple files can be selected. To select multiple files, point the mouse cursor to the filename you want
to select and click the left mouse button while holding the Ctrl key down to select files one at a time.
Each plot will be automatically scaled to fit its individual data, unless the scale is frozen using the Graph
Option command. In this case, all plots will have the same frozen scale.
The Graph Option, Color and Legend, and Font commands allow you customize your overlay plot.
This command is disabled if there is no currently active data or if the current plot is not a parallel plot.
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CH Instruments Model 900D Series
Replot Parallel command
Use this command to display the most recent Parallel plot. This is useful after clicking the Present Data
Plot button or when loading plots from file.
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Manage Parallel command
Use this command to open the Manage Files dialog box. This will allow you to add, reorder, and remove
files from a multi-file plot.
The Manage Overlay or Manage Parallel command presents this dialog box.
This dialog box displays a list of all files being plotted with the current file. As in older versions of the
program, the current file is always the first plot, so it cannot be moved or removed. Click OK to confirm
all changes.
Add
Clicking this button has the same effect as the Add Data to Overlay or Add Data to Parallel command.
Move Up / Down
Select multiple files by holding down Ctrl or Shift key and left-clicking. You can then to move your
selection up or down in the list by clicking the appropriate Move button. The current file is always the
first plot, so you will not be able to move your selection above it.
Remove
Select file(s) as when using Move Up / Down. Once you click Remove, these files will be removed from
your plot.
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Zoom In command
Use this command to magnify the data plot.
This command has a toolbar button:
To enter zoom mode, either click on the toolbar button or on its entry in the Graphics menu. A check
mark appears next to the menu item when zoom mode is enabled, and its toolbar button will be
depressed.
Once in zoom mode, the mouse cursor will appear as an up arrow in the data plot area. To zoom in, leftclick and drag between diagonal corners of the box containing the area you want to view more closely.
Release the mouse button to zoom in.
To zoom back out and exit zoom mode, click the Zoom In command or toolbar button again.
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Manual Results command
Use this command to report peaks, wave potentials, currents, and area manually. You can determine
the linear baseline(s) for a peak or wave graphically.
This command has a toolbar button:
To enter manual mode, either click on the toolbar button or on its entry in the Graphics menu. When
manual mode is enabled, the menu entry and toolbar button will both be marked.
Once in manual mode, the mouse cursor will appear as an up arrow in the data plot area.
In order to report a peak or wave correctly, you must use the Peak Definition command to define the
peak shape as Gaussian, diffusive, or sigmoidal. You can also choose between reporting peak (or wave)
potential, half peak (or wave) potential, peak (or wave) currents, and/or peak area.
For a Gaussian peak, the baseline is determined by two points straddling the peak. Left-click at one
point, drag to the other point, and release the left mouse button. A vertical line from peak to baseline will
appear, with corresponding numerical values reported at the right side of the plot.
For a diffusive peak, the baseline is determined by extending the foot before the peak. Left-click at the
foot, drag past the peak potential, and release the left mouse button. A vertical line from peak to
baseline will appear, with corresponding numerical values reported at the right side of the plot. Notice
that half peak area is reported in this case.
For a sigmoidal wave, two baselines are needed: one at the foot and one at the plateau of the wave. Leftclick and drag to draw each baseline. A vertical line connecting the two baselines and crossing the
middle of the wave will appear, with corresponding numerical values reported at the right side of the plot.
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Peak Definition command
Use this command to define the peak shape as Gaussian, diffusive, or sigmoidal. You can also choose
to report peak (or wave) potential, half peak (or wave) potential, peak (or wave) currents, and/or peak
area.
The selected peak definition is used by both automatic and manual result reporting.
This command opens a technique-dependent dialog box: ACV, CV, IT, SWV, other.
This command has a toolbar button:
The general Peak Definition dialog box is:
General Peak Definition options are:
Peak Shape
Define the peak shape as Gaussian, diffusive, or sigmoidal as appropriate to your data. A default peak
shape is assigned based on the selected experimental technique. However, you can change this setting.
Report Option
You can also choose to report peak (or wave) potential, half peak (or wave) potential, peak (or wave)
currents, and/or peak area.
Peak or wave search potential range
Depending on peak shape, the peak search potential range can be adjusted. For a broader peak or
wave, the search potential range should be larger. The search potential range should include both sides
of the peak or wave.
This parameter is only meaningful for automatic result reporting.
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X-Y Plot command
This command opens the X-Y Plot dialog box.
Use this command to input data manually for plotting. Linear curve fitting can also be performed.
After the data have been input, click the OK button to generate the plot. The resulting X-Y plot is
temporary and will disappear if other data display commands are invoked. You can use the Graph Option
, Color and Legend, and Font commands to customize your plot. You can also save your data, overlay
your data plots, or make parallel plots.
The X-Y Plot command presents this dialog box.
The following options allow you to edit your data and enter plot options:
X, Y Data Array Editor
Enter your own X Y data points. Use comma or space to separate X and Y values, one pair per line:
x1, y1
x2, y2
x3, y3
......
Overlay Plot
Click this button to plot multiple sets of data in a single graph. To display both data markers and lines,
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save your data with two different names and select proper legends with the Color and Legend command.
To freeze the axes, use the Graph Option command.
The program will display the Overlay Data Display dialog box so you can select the data files you want
to plot along with the data in the X, Y Data Array Editor. Multiple files can be selected.
The plot will be automatically scaled to fit the data in the X, Y Data Array Editor. If both X and Y values
fall into the plot scale, the data point will be plotted.
Parallel Plot
Click this button to plot multiple sets of data side by side.
The program will display the Parallel Data Display dialog box so you can select the data files you want
to plot along with the data in the X, Y Data Array Editor. Multiple files can be selected.
Each plot will be automatically scaled to fit its individual data unless the scale is frozen using the Graph
Option command. In this case, all plots will have the same frozen scale.
Plot
Use this command to plot the data entered in the X, Y Data Array Editor. The plot will be automatically
scaled to fit the data range unless the scale is frozen using the Graph Option command.
X, Y Axis Title, Unit
Specify titles and units/dimensions for the X and Y axes.
Header
Enter the desired title (header) for the data. To display the header on the top of the plot, check the
Header box using the Graph Option command.
Note
Enter any comments about the plot. The note will not be displayed on the plot, but will be saved in the
data file. It allows you to put additional comments about the data and is well-suited for a brief description
of the purpose and conditions of the experiment.
Read
Use this command to read data from file.
Save
Use this command to save data to file. XY titles, units, header, and note will be saved along with the
data.
Linear Curve Fitting
Toggle least squares fit; if this box is checked, a best fit straight line will also appear on the plot.
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Peak Parameter Plot command
This command opens the Peak Parameter vs Scan Rate Plot dialog box. Use this command to plot
peak current or potential against the scan rate. This command can also perform a linear fit to the data.
This command works only for cyclic voltammetric (CV) or linear sweep voltammetric (LSV) data. For CV
data, the system only searches for the currently active data segment.
After specifying the peak potential window and selecting the proper files, click OK to render the plot. The
resulting plot is temporary and will disappear if other data display commands are invoked. You can use
the Graph Option, Color and Legend, and Font commands to customize your plot.
The Peak Parameter Plot command opens this dialog box.
Peak Potential Window
Specify the potential range in which the program will search for peaks. The first peak in this potential
range will be used for plotting.
Type of Plot
Plot peak current versus the scan rate, peak current versus the square root of the scan rate, or peak
potential versus the logarithm of the scan rate.
For a reversible surface reaction, the peak current is proportional to the scan rate. For a reversible
diffusive system, the peak current is proportional to the square root of the scan rate.
The peak potential should be independent of the scan rate for a reversible reaction. A change in peak
potential with scan rate indicates either slow kinetics or chemical complexity.
Linear Curve Fitting
Checking this box will generate a linear least squares best fit line on the plot.
Select Files
Select data files to be plotted (CV or LSV only). Select at least three data files obtained at different scan
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rates.
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Semilog Plot command
This command opens the Current-Potential Semilog Plot dialog box.
Use this command to display a current-potential semilog plot. This is useful in data analysis for steadystate responses. One can also convert a diffusive or peak-shaped response by semi-integral or full
integral to a sigmoidal curve and display a semilog plot.
For a reversible reaction, the intercept on the potential axis is the half wave potential and the slope
should be 0.059/n V. Any deviation from this expected slope indicates slow kinetics or complexity of the
electrode reaction.
This command can also perform a linear fit to the data.
After specifying the peak potential window and selecting the proper files, click OK to render the plot. The
resulting plot is temporary and will disappear if other data display commands are invoked. You can use
the Graph Option, Color and Legend, and Font commands to customize your plot.
The Semilog Plot command presents this dialog box.
Potential Window
Enter the range of potential values to be plotted. The potential window should be near the half wave
potential and within ±0.059/n V. Data points outside the specified potential window will be ignored.
Linear Curve Fitting
Checking this box will generate a linear least squares best fit line on the plot.
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Special Plot command
Use this command to display special plots if available.
For linear sweep voltammetry (LSV), this command opens the Polarization Resistance Plot dialog box.
The resulting plot is temporary and will disappear if other data display commands are invoked. You can
use the Graph Option, Color and Legend, and Font commands to customize your plot.
The Special Plot command presents this dialog box for the LSV technique.
After this command is invoked, the program will check for a potential with zero current. If found, this
potential is set as E (V, I=0). Otherwise, a warning "Potential at zero current not found" will be issued.
After specifying the center potential and potential range, click OK to construct the polarization
resistance plot.
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Graph Options command
This command opens the Graph Options dialog box.
Use this command to selectively turn on or off plot captions, grids, axis inversion. You can also freeze
axes, customize axis titles, and write notes that can be saved together with the data. Most other
parameters will be saved when you exit the program and reloaded when you restart the program.
This command has a toolbar button:
The Graph Options command presents this dialog box.
Depending on the currently selected experimental technique, specialized options may also be available.
For context-specific details, click the Help button in the currently open dialog box.
The following options are available for all techniques:
Screen
Uncheck the corresponding box to hide the header, axis, baseline, parameters, or results on screen.
The header is the title shown at the top of the plot, entered in the Header field in this dialog box.
The baseline is drawn to visually define a peak or wave.
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Screen options are independent of the printer options described below.
Printer
Uncheck the corresponding box to hide the header, axis, baseline, parameters, or results on printed
output.
Printer options are independent of the screen options described above.
Grid and Inv
Uncheck the corresponding box to hide the X or Y grid or to disable axis inversion.
Check X or Y inversion to flip the X or Y axis temporarily. To invert axis polarity permanently, use the
System command in the Setup menu.
X, Y Freeze
Freeze the X or Y axis range by checking the corresponding box and enter the desired min and max.
The X and Y axis can be frozen independently.
When the corresponding box is unchecked, the X or Y scale will revert to the original scale of the
present plot.
In SECM mode, the Z axis can also be frozen similarly.
Due to the program requirement for an integer number of ticks, an axis may be unable to be frozen at the
scale you entered
X, Y Title
The program automatically provides default axis titles for each electrochemical technique. To override
these defaults, check the corresponding box and enter the desired title.
Unit
Specify the units or dimensions of customized axis titles.
X, Y Scale
These values change the size of the plot (the default full-size value is 1). This is particularly useful when
you want to print the plot for publication or paste the plot into a word processor.
Cursor Lock to Data Points
This option controls the behavior of the mouse cursor in the plot area. The X and Y coordinates of the
cursor will be displayed in both modes.
When Lock is selected, the cursor will be locked to data points; when you move the mouse in the X
direction, the cursor will move along the data curve. This is particularly useful for identifying data points.
When Free is selected, the cursor will move freely in the XY plane.
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This option is not available for the SECM technique.
Current Density
Check this box to display current density.
Electrode Area
This value is used to calculate the current density.
E vs Reference Electrode
Specify the name of the reference electrode used in the experiment in the Ref. Electrode field, e.g., "Ag/
AgCl".
The default potential axis title is “Potential / V”. Check the "E vs Reference Electrode" to append the
Ref. Electrode field to the potential axis title, e.g., “Potential / V vs Ag/AgCl".
Header
Enter your header in this field. To display this header at the top of your plot, check the Header box under
Screen and/or Printer options in this dialog box.
Note
Enter your notes in this field. Notes will not be displayed on the screen or printed, but will be saved in
the data file, allowing you to add comments about the experiment and remind yourself later about the
purpose and the conditions of the experiment.
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Color and Legend command
This command opens the Color Selection dialog box.
Use this command to specify color and legend options for your graphical plots. You can change the
color of the background, axes, grid, and data curves. You can also change marker/line options
("Legend") for data curves and the grid.
Color and legend options will be saved when you exit the program and will be reloaded when you restart
the program.
To change text color, use the Font command instead.
This command has a toolbar button:
The Color and Legend command presents a dialog box.
The following options allow you to specify the colors and the data marker/line options of the plot:
Curve #
Curve 0 indicates the currently active data. Curves 1-9 indicate Overlay Plots.
Color
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You can specify the color of data curves, the grid, the background, and the axes by clicking the
corresponding Change button to open a system Color dialog box.
To adjust text color, use the Font command instead.
Legend
Specify the style ("legend") of the marker/line style for the data curves and grid, e.g., line, point, circle.
When the legend is chosen to be "point", data curves curve or the grid may not print correctly. This has
been found to be a printer-specific problem. Please consult your printer documentation or choose a
different legend if this occurs.
Size
Specify the marker size/line thickness.
Interval
Setting this value to N plots every Nth data point (default 1). A larger value of Interval lowers your data
point, which is useful for Overlay Plots or different legends.
Default
Clicking this button will reset all colors and legends to the program's default values.
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Font command
This command opens the Font Selection dialog box.
Use this command to adjust the appearance of the text used in the plot. The font, style, size, and color
can be adjusted separately for all text elements. You can also rotate the Y axis title for printing.
Font options will be saved when you exit the program and will be reloaded when you restart the program.
This command has a toolbar button:
The Font command presents a dialog box.
To change the font, style, size or color of the text, click the Change button to the right of the
corresponding item.
The Y axis title should read from bottom to top. However, different printers have been found to follow
different character rotation conventions, so you may have to adjust the rotation angle to obtain the
correct orientation for your printer.
Pressing the Default button will reset all font settings to the program defaults.
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Copy to clipboard command
Use this command to copy the currently displayed plot to the clipboard. You can then paste it into a
word processor or any other Windows based program. This command will work during a run or a digital
simulation. Alternatively, use the Alt+PrtScn system keyboard shortcut.
This command has a toolbar button:
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DataProc Menu
Chapter 7
DataProc Menu
The DataProc menu offers the following commands:
Smoothing
Smooth data by least squares or bandwidth filtering.
Derivatives
Compute numerical derivatives of data up to 5th order.
Integration
Integrate data numerically.
Semiinteg and Semideriv Take semi-integral or semi-derivative.
Interpolation
Insert interpolated data points.
Baseline Fitting & Subtract.Fit and subtract a polynomial baseline from data.
Linear Baseline Correction Correct baseline visually.
Data Point Removing
Remove data points visually.
Data Point Modifying
Modify data points visually.
Background Subtraction
Subtract background data from present data.
Signal Averaging
Average multiple data sets.
Mathematical Operation
Perform mathematical operation on X or Y data.
Fourier Spectrum
Compute Fourier spectrum of data.
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Smoothing command
This command opens the Smoothing dialog box. Use this command to smooth the currently active data.
This command has a toolbar button:
The Smoothing command presents this dialog box.
The following options allow you to specify the smoothing method and corresponding parameters:
Method Selection
Least square and Fourier transform (FT) smoothing options are available.
Least Square Point
Least square smoothing requires an odd number of points between 5 and 49. More points will result in
better smoothing, but may also cause distortion.
The program performs least square smoothing using the algorithm of Savitzky and Golay. For more
details about this algorithm, please refer to "Smoothing and Differentiation of Data by Simplified Least
Squares Procedures", Anal. Chem., 36, 1627-1639 (1964).
FT Cutoff (1/s or 1/V)
Specify the filter cutoff frequency. For a time-based experiment (e.g., CA, CC, TB), the Fourier-conjugate
frequency has units of 1/s or Hz; voltammetry, it has units of 1/V. In the latter case, the physical
meaning is how many signal cycles are allowed in one volt of potential range. A lower cutoff will result in
better smoothing, but may also cause distortion.
The program performs Fourier transform smoothing using the algorithm of D.E. Smith et al. For more
details about this algorithm, please refer to "Some Observations on Digital Smoothing of
Electroanalytical Data Based on the Fourier Transformation", Anal. Chem., 45, 277-284 (1973).
In general, Fourier transform smoothing is very effective. Distortion may be minimal, if the signal band is
well separated from the noise band. However, this method is more time-consuming than least square
smoothing.
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Smooth After Run
Check this box to enable automatic smoothing after each experimental run. Certain techniques do not
allow smoothing (e.g., TAFEL, BE, IMP). This option can also be turned on or off from the Run Status
command under the Control menu.
Override Present Data
Check this box to replace the currently active data with the resulting smoothed data. If this box is not
checked, the smoothed data will only be displayed, without overriding the currently active data, and
invoking the Present Data Plot command will display the original data.
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Derivatives command
This command opens the Derivative dialog box. Use this command to compute the numerical derivative
of the currently active data.
After performing a first order derivative, the Y axis has dimensions of Y unit / X unit (A/V for voltammetry,
A/s for i-t curves, etc.). The new unit is not explicitly expressed, but you should be aware of it.
This command has a toolbar button:
The Derivatives command presents this dialog box.
Derivative Order
Up to fifth order derivatives can be taken.
Least Square Point
Derivative computation requires an odd number of points between 5 and 49. More points will result in
better smoothing, but may also cause distortion. Numerical differentiation will inherently amplify high
frequency noise, so a relatively large number of points should be considered. More points will result in
less noisy derivative data, but may also cause distortion.
The program performs numerical differentiation using the algorithm of Savitzky and Golay. For more
details about the Savitzky and Golay algorithm, please refer to "Smoothing and Differentiation of Data by
Simplified Least Squares Procedures", Anal. Chem., 36, 1627-1639 (1964).
Override Present Data
Check this box to replace the currently active data with the resulting derivative data. If this box is not
checked, the derivative data will only be displayed, without overriding the currently active data, and
invoking the Present Data Plot command will display the original data.
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Integration command
This command opens the Integration dialog box. Use this command to integrate the currently active
data.
After performing integration, the Y axis has dimensions of Y unit × X unit (A/V for voltammetry, coulombs
for i-t curves, etc.). The new unit is not explicitly expressed, but you should be aware of it.
The Integration command presents this dialog box.
Override Present Data
Check this box to replace the currently active data with the resulting integrated data. If this box is not
checked, the integrated data will only be displayed, without overriding the currently active data, and
invoking the Present Data Plot command will display the original data.
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Semiinteg and Semideriv command
This command opens the Semi-derivative and Semi-integral dialog box.
Semi-derivatives and semi-integrals can be used for a variety of purposes. For instance, the semiderivative can be used to convert a diffusive peak to a Gaussian peak. This allows higher resolution and
facilitates measurement. A diffusive peak can also be converted to a sigmoidal wave to yield a timeindependent steady state current plateau. In polarographic theory, current-potential semilog analysis can
be used to interpret the resulting data.
This command has a toolbar button:
The Semiinteg and Semideriv command presents this dialog box.
Order Selection
Both semi-derivative and semi-integral can be computed.
Override Present Data
Check this box to replace the currently active data with the resulting convoluted data. If this box is not
checked, the convoluted data will only be displayed, without overriding the currently active data, and
invoking the Present Data Plot command will display the original data.
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Interpolation command
This command opens the Interpolation dialog box. Use this command to insert additional data points into
the currently active data.
The Interpolation command presents this dialog box.
Data Insertion Density
The larger the multiplier, the more points will be inserted between the existing data points. When the
number of data points exceeds the available memory size, a warning will be given and the command will
terminate. The multiplier can only be a power of 2. Fourier transform is used in this case.
Override Present Data
Check this box to replace the currently active data with the resulting interpolated data. If this box is not
checked, the interpolated data will only be displayed, without overriding the currently active data, and
invoking the Present Data Plot command will display the original data.
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CH Instruments Model 900D Series
Baseline Fitting & Subtraction command
This command opens the Baseline Fitting & Subtraction dialog box.
Use this command to fit the baseline and subtract the fitting curve from the currently active data. This is
very useful for peak evaluation.
In order to perform Baseline Fitting and Subtraction, you need to specify the potential on both sides of
the peak base, the algorithm, and the order of fit.
Baseline Fitting and Subtraction only works for certain peaks and experimental techniques.
If more than one segment of data is available, such as CV data, you can choose the segment to operate
on with the Graph Option command under the Graphics menu.
This command has a toolbar button:
The Baseline Fitting & Subtraction command presents this dialog box.
The following options allow you to select fitting parameters and data file options:
Two sides of Peak Foot
When fitting the baseline, data points corresponding to peaks must not be included. In a mountaineering
analogy, the user must mark off the "feet" (data interval) of each peak. Adjusting peak foot values can
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improve your baseline fit.
If there are multiple peaks, feet need to be specified for each peak (up to 5), or alternatively, you can
also specify a large potential or time range covering several peaks.
Baseline Fitting Algorithm and Orders
Orthogonal Least Square and Least Square algorithms are available for fitting the baseline, both utilizing
polynomial fits. The Baseline Fitting Orders field specifies the order of the polynomial fit: first order
stands for linear fitting, aX+b; second order stands for aX2+bX+c fitting; and so on.
Save to Override Original Data
This option determines what data are output upon clicking the "OK" button.
When “No Action” is selected, the original data will be plotted with the fitted baseline, and the original
data remains unchanged.
When “Difference” is selected, the original data will be replaced by the difference between the original
data and the fitted baseline.
When “Baseline” is selected, the fitted baseline data will be saved.
View Baseline
This button plots the original data and the fitted baseline together to evaluate the fitting results. Use this
command to preview the quality of the baseline fit. The original data remains unchanged. Use the
Present Data Plot command under the Graphics menu to display the original data.
If peak defining lines obstruct your view, you can turn off the “Screen Baseline” option by using the
Graph Options command under the Graphics menu.
View Difference
This button plots the difference between the original data and the fitted baseline. This is helpful when
evaluating the fitting results. Use this command to preview the quality of the baseline fit. The original
data remains unchanged. Use the Present Data Plot command under the Graphics menu to display the
original data.
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CH Instruments Model 900D Series
Linear Baseline Correction command
This command opens the Baseline Correction dialog box.
Use this command to visually correct the baseline of the currently active data. You can compensate a
sloped baseline and shift the DC level of the curve.
The Linear Baseline Correction command presents this dialog box.
To perform baseline correction, click the OK button first. The mouse cursor will change to an up arrow.
Left-click at the starting point and drag to define a sloped baseline. When the mouse button is released,
this line is subtracted from your data. X values not covered by the line will be unaffected.
To shift the DC level, left-click and drag to create a horizontal line, which defines the new zero of the
entire curve. You don't have to draw a line to cover the entire X range.
If more than one segment of data is available, such as CV data, you can choose the segment to operate
on with the Graph Option command under the Graphics menu.
This command is applied only once per invocation. To compensate or shift the baseline more than once,
invoke this command repeatedly.
Override Present Data
Check this box to replace the currently active data with the resulting baseline corrected data. If this box
is not checked, the baseline corrected data will only be displayed, without overriding the currently active
data, and invoking the Present Data Plot command will display the original data.
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Data Point Removing command
This command opens the Data Point Removing dialog box. Use this command to remove unwanted data
points from the beginning or end of the currently active data.
The Data Point Removing command presents this dialog box.
Remove Beginning Data Points
Specify the number of data points to be removed from the beginning of the data set. If this number is
zero, no points will be removed from the beginning.
Remove Ending Data Points
Specify the number of data points to be removed from the end of the data set. If this number is zero, no
points will be removed from the end.
Override Present Data
Check this box to replace the currently active data with the new data after data point removal. If this box
is not checked, the new data will only be displayed, without overriding the currently active data, and
invoking the Present Data Plot command will display the original data.
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7.9
CH Instruments Model 900D Series
Data Point Modifying command
This command opens the Data Point Modifying dialog box. Use this command to visually modify the
data points of the currently active data, e.g., to correct data points due to a bad mercury drop.
The Data Point Modifying command presents this dialog box.
To modify data points, click the OK button first. The mouse cursor will change to an up arrow.
When you move the mouse cursor in the data display region, crosshairs will appear at the data point
corresponding to the X axis position of the mouse cursor. Move the mouse horizontally to select the data
point you want to modify. When the crosshairs appear at the selected point, left-click and drag vertically
to move the data point, and release the mouse button to finish. The old data point will be erased and a
new data point will appear at the new position.
Segment
Choose the data set (segment) you want to modify. The range of valid values will depend on the
electrochemical technique used.
Override Present Data
Check this box to replace the currently active data with the modified data. If this box is not checked, the
modified data will only be displayed, without overriding the currently active data, and invoking the Present
Data Plot command will display the original data.
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Background Subtraction command
This command allows you to calculate the difference between two data sets. First you have to measure
the blank solution, save the data file. Then run the sample. You can now use this command to do a
background subtraction.
In order to do a background subtraction, the background data should be the same type of experiment
and the same X data array. Otherwise an error message will be issued, and the command will be
terminated.
This command presents the following dialog box:
This allows you to select the background data file that will be subtracted from the currently active data.
File name
Type or select the filename you want to subtract. This box lists files with the extension you select in the
"Files of type" box.
You don't have to type the extension. The program will automatically attach an extension of ".bin" to the
filename. Other extensions are not allowed.
Files of type
Select the type of file you want to subtract. Only the ".bin" type (binary data file) will be available.
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Signal Averaging command
This command allows you to perform signal averaging between the currently active data and files saved
on disk. The currently active data is always included in the averaging, which is computed by simply
adding together several sets of data and dividing the result by the number of data sets. Data sets whose
X values differ from the currently active data will be ignored.
This command presents the following dialog box:
This allows you to select the files that will be averaged with the currently active data.
File name
Type or select the filename(s) you want to average. The box above lists files with the extension you
select in the "Files of type" box.
Multiple files can be selected for averaging.
You don't have to type the extension. The program will automatically attach an extension of ".bin" to the
filename. Other extensions are not allowed.
Files of type
Select the type of file you want to convert. Only the ".bin" type (binary data file) will be available.
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DataProc Menu
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195
Mathematical Operation command
This command opens the Math Operation dialog box.
Use this command to perform mathematical operations on the currently active data. The allowed
operations are addition, subtraction, multiplication, division, exponential, logarithm, square, square root,
and reciprocal, applicable to both X and Y data values.
The Mathematical Operation command presents this dialog box.
Operation Selection
Select the operation you want to apply to the data. If addition, subtraction, multiplication or division is
chosen, you have to provide the second operand in the appropriate field.
Data Selection
Select either the X data array or the Y data array as the target of the mathematical operation.
Override Present Data
Check this box to replace the currently active data with the operated data. If this box is not checked, the
operated data will only be displayed, without overriding the currently active data, and invoking the
Present Data Plot command will display the original data.
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7.13
CH Instruments Model 900D Series
Fourier Spectrum command
This command opens the Fourier Spectrum dialog box. Use this command to obtain the Fourier
spectrum of the currently active data.
The Fourier Spectrum command presents this dialog box.
X Scale
The X data array of the Fourier spectrum can have an nth component, a 1/s scale, or a 1/V scale,
depending on your choice.
An nth component scale is generally used. It is available for all techniques. Its physical meaning is
derived from experimental parameters.
The 1/s and 1/V scales have a clear physical meaning. For time-based experiments, the 1/s scale
should be used, and the 1/V is invalid; for voltammetric experiments, the 1/V should be used since the
1/s scale may not be valid. CV and LSV experiments are special cases; both 1/s and 1/V scales can be
used here.
Y Scale
The Y data array contains the Fourier coefficients and can have either a linear or logarithmic scale.
Override Present Data
Check this box to replace the currently active data with the Fourier spectrum data. If this box is not
checked, the Fourier spectrum data will only be displayed, without overriding the currently active data,
and invoking the Present Data Plot command will display the original data.
© 2014 CH Instruments, Inc.
Analysis Menu
Chapter 8
Analysis Menu
The Analysis menu offers the following commands:
Calibration Curve
Standard Addition
Data File Report
Time Dependence
Special Analysis
© 2014 CH Instruments, Inc.
Plot a calibration curve.
Determine concentration by Standard Addition.
Generate report file.
Plot time-dependence of concentration.
Perform special analysis for select techniques (if available).
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Calibration Curve command
This command opens the Calibration Curve dialog box, which allows you to specify options for calibration
curve calculation and/or plotting.
The Calibration Curve command presents this dialog box.
Standard #
Enter the concentration and peak height/current obtained from standard solutions.
Unknown
Enter the peak height of the unknown species if available to allow calculation of its concentration.
X Axis Title
Enter the desired X-axis title (e.g., Concentration) to be plotted.
X Axis Unit
Enter the X Axis unit or dimension (e.g., ppm or M) to be plotted.
Y Axis Title
Enter the desired Y axis title (e.g., Peak Current) to be plotted.
Y Axis Unit
Enter the signal unit or dimension (such as A) to be plotted.
Header
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Enter the desired title (header) for the data. To display the header on the top of the plot, check the
Header box using the Graph Option command.
Note
Enter any comments about the plot. The note will not be displayed on the plot, but will be saved in the
data file. It allows you to put additional comments about the data and is well-suited for a brief description
of the purpose and conditions of the experiment.
Read
Use this command to read data from file.
Save
Use this command to save data to file. XY titles, units, header, and note will be saved along with the
data.
Calculate
Use this command to calculate the slope, intercept and correlation coefficient of the calibration curve. If
the unknown peak height is given, the unknown concentration will also be calculated.
Plot
Use this command to plot the calibration curve. The plot will be automatically scaled according the data
range. To freeze the scale, please use the Graph Option command.
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Standard Addition command
This command opens the Standard Addition dialog box.
Use this command to calculate the concentration of the unknown by standard addition. Namely, the
unknown is measured first and its peak height is recorded. Then the standard solutions are added
repeatedly, measuring the peak height of the unknown after each standard addition. Usually, the added
volume is much smaller than the total volume in order to maintain the sample compositions and have the
same matrix effect. The increment concentration should be comparable to the unknown.
The Standard Addition command presents this dialog box.
The following options allow you to specify data calculating the concentration of the unknown species or
plotting:
Unknown
Enter the peak height of the unknown species to allow calculation of its concentration.
Addition #
Enter the concentration and peak height/current after adding standard solutions.
X Axis Title
Enter the desired X-axis title (e.g., Concentration) to be plotted.
X Axis Unit
Enter the X Axis unit or dimension (e.g., ppm or M) to be plotted.
Y Axis Title
Enter the desired Y axis title (e.g., Peak Current) to be plotted.
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Y Axis Unit
Enter the signal unit or dimension (such as A) to be plotted.
Header
Enter the desired title (header) for the data. To display the header on the top of the plot, check the
Header box using the Graph Option command.
Note
Enter any comments about the plot. The note will not be displayed on the plot, but will be saved in the
data file. It allows you to put additional comments about the data and is well-suited for a brief description
of the purpose and conditions of the experiment.
Read
Use this command to read data from file.
Save
Use this command to save data to file. XY titles, units, header, and note will be saved along with the
data.
Calculate
Use this command to calculate the slope, intercept and correlation coefficient of the standard addition
curve. If the unknown peak height is given, the unknown concentration will also be calculated.
Plot
Use this command to plot the standard addition curve. The plot will be automatically scaled according
the data range. To freeze the scale, please use the Graph Option command.
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CH Instruments Model 900D Series
Data Report command
This command opens the Data File Report dialog box.
Use this command to generate a report for stored data files. Options are available to specify peak
potential windows, slope/intercept of calibration curves, destination file name, etc.
The Data File Report command presents this dialog box.
The following options allow you to specify peak potential windows, slope/intercept of calibration curves,
and select the data files to be reported:
Compound
Enter the names of the species to be analyzed. Up to four compounds can be searched and reported.
Ep From and Ep To
Enter the peak potential range. Ep From and Ep To cannot be equal. When the program searches for
peaks, the first peak in the specified range will be selected. Ranges should not overlap for different
species.
Slope
Enter the slope of the calibration curve for each species to calculate the concentration of the compound.
A value must be specified for each species. The program will warn the user if Conc. Data Type is
selected and a slope is zero.
Intercept
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Enter the intercept of the calibration curve for each species to calculate the concentration of the
compound. A value must be specified for each species.
Peak Shape
Select the peak shape that is most appropriate for your data. The currently available choices are
Gaussian, diffusive, and sigmoidal.
Data Type
Choose between original data, semi-derivative, and first derivative to report the concentration.
Number of Species
Enter the number of species for the data file report.
Concentration Unit
Enter the units/dimension of concentration (e.g., ppm or M).
Report Filename
Enter the report filename if you want to save the report text file. If a file with the specified name already
exists, an overwrite warning will be issued. If no filename is specified, the report will be shown but not
saved.
Report Data Type
Either concentration or peak current can be reported.
Header
Enter the desired title (header) for the data. To display the header on the top of the plot, check the
Header box using the Graph Option command.
Note
Enter any comments about the plot. The note will not be displayed on the plot, but will be saved in the
data file. It allows you to put additional comments about the data and is well-suited for a brief description
of the purpose and conditions of the experiment.
Read
Use this command to read data from file.
Save
Use this command to save data to file. XY titles, units, header, and note will be saved along with the
data.
Report
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Use this command to generate the data file report.
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Analysis Menu
8.4
205
Time Dependence command
This command opens the Time Dependence dialog box.
Use this command to generate a report or plot for the time dependence of peak heights or
concentrations from stored data files. The program will search for peak height or concentration in each
data file, sorted in chronological order relative to the earliest experiment.
The Time Dependence command presents this dialog box.
The following options allow you to specify peak potential windows, slope/intercept of calibration curves,
and select the data files whose time dependence is to be reported or plotted:
Ep From and Ep To
Enter the peak potential range. Ep From and Ep To cannot be equal. When the program searches for
peaks, the first peak in the specified range will be selected. Ranges should not overlap for different
species.
Slope
Enter the slope of the calibration curve for each species to calculate the concentration of the compound.
A value must be specified for each species. The program will warn the user if Conc. Data Type is
selected and a slope is zero.
Intercept
Enter the intercept of the calibration curve for each species to calculate the concentration of the
compound. A value must be specified for each species.
Peak Shape
Select the peak shape that is most appropriate for your data. The currently available choices are
Gaussian, diffusive, and sigmoidal.
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Data Type
Choose between original data, semi-derivative, and first derivative to report the concentration.
Y Axis Title
Enter the desired Y axis title (e.g., Concentration or Peak Current) to be plotted.
Y Axis Unit
Enter the units/dimension of concentration (e.g., ppm or M).
Report Name
Enter the report filename if you want to save the report text file. If a file with the specified name already
exists, an overwrite warning will be issued. If no filename is specified, the report will be shown but not
saved.
Report Data Type
Either concentration or peak current can be reported.
Header
Enter the desired title (header) for the data. To display the header on the top of the plot, check the
Header box using the Graph Option command.
Note
Enter any comments about the plot. The note will not be displayed on the plot, but will be saved in the
data file. It allows you to put additional comments about the data and is well-suited for a brief description
of the purpose and conditions of the experiment.
Read
Use this command to read data from file.
Save
Use this command to save data to file. XY titles, units, header, and note will be saved along with the
data.
Report
Use this command to generate the time dependence report.
Plot
Use this command to generate the time dependence plot.
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Analysis Menu
8.5
207
Special Analysis command
Currently this command is only active for TAFEL measurements. Use this command to calculate the
corrosion rate from Tafel experiment results by opening the Corrosion Rate Calculation dialog box.
When TAFEL data are available, invoking the Special Analysis command presents this dialog box.
Data Segment
If you have more than one segment of data, you need to specify which segment of data to use in the
corrosion rate calculation.
Equilibrium E
The program will automatically estimate the equilibrium potential by searching for the potential value
where current is closest to zero. You can manually override this default estimate.
Cathodic Tafel Slope Potential Range
By default, the cathodic Tafel slope potential range starts at 60 mV more negative than the equilibrium
potential and has a default range of 100 mV. You can manually override this default potential range.
Anodic Tafel Slope Potential Range
By default, the anodic Tafel slope potential range starts at 60 mV more positive than the equilibrium
potential and has a default range of 100 mV. You can manually change this potential range.
Calculate
Once data segment, equilibrium potential, and anodic and cathodic potential ranges are properly set,
click this button to calculate the cathodic and anodic Tafel slope, linear polarization resistance (in
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ohms), and the corrosion current (in amperes).
© 2014 CH Instruments, Inc.
Sim Menu
Chapter 9
Sim Menu
The Setup menu offers the following commands:
Mechanism
CV Simulate
CV Fitting
© 2014 CH Instruments, Inc.
Set CV or IMP simulation parameters.
Run CV simulation.
Run CV data fitting.
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Mechanism command
Select instrument models include built-in CV simulation, impedance simulation, and impedance data
fitting software.
For most techniques, this command opens the Digital Simulation dialog box. However, when the A.C.
Impedance technique is selected under the Setup menu, this command will instead launch the
impedance simulator.
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Sim Menu
9.1.1
211
Digital Simulation dialog box
The Mechanism command presents this dialog box. (This section, of course, applies only when the A.C.
Impedance technique is not active.)
Before running a simulation, use this dialog box to set the reaction mechanism, species concentrations,
kinetic, experimental, and other parameters. All settings can be saved to and read from file. The
equilibrium concentration can also be checked.
Mechanism Edit
This edit box allows you to edit the reaction mechanism. The Mechanism Select list contains several
pre-defined mechanisms which when clicked automatically fill out the Mechanism Edit box. Type directly
in the edit box to input a user-defined mechanism (select models only).
To write your own mechanism, use a single letter (A-Z) to represent each chemical species. The letter
"e" is reserved for electron transfer. The program will treat uppercase and lowercase letters as identical
and ignore any spaces.
The program can simulate any reasonable combination of electron transfer, 1st order, and 2nd order
chemical reactions, up to 11 reactions and 9 chemical species. Example usage:
A
A
A
A
A
+e=B
-e=B
=B
=B+C
+B=C
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(reduction)
(oxidation)
(isomerization)
(dissociation)
(combination)
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A+B=C+D
(general reaction)
Mechanism Select
There are 10 pre-defined mechanisms covering the most commonly encountered reactions. The first item
is "User Input". Only Model 630 and Model 660 will accept the user defined mechanism.
Some mechanisms not listed can still be obtained from the pre-defined mechanisms. For instance,
EEC, ECC, and CEC mechanisms can be obtained from the ECEC mechanism by setting the
appropriate kinetic parameters to null. If you define the heterogeneous electron transfer rate ko to zero,
the corresponding electron transfer step will have no effect. If you define the forward and reverse rate
constants of a chemical reaction to zero, the corresponding chemical reaction will have no effect.
Clicking on a pre-defined reaction mechanism will automatically fill out the Mechanism Edit box. If "User
Input" is selected, the Mechanism Edit box will be empty.
System under study
A diffusive or adsorptive system can be simulated. For diffusive systems, planar diffusion is assumed.
For adsorptive systems, it is assumed that the adsorption obeys the Langmuir isotherm, and both
oxidized form and reduced form are strongly adsorbed.
Dimensionless current
When this box is checked, the program will calculate the dimensionless current, which is useful for
comparison with other theoretical predictions. When this box is not checked, current will be calculated
according to the concentration, electrode area, and time scale of the experiment.
Initial Concentration at the equilibrium
When this box is checked, the program will first calculate equilibrium concentrations and then use the
computed values as the initial conditions for the simulation. The equilibrium state is calculated according
to the kinetic parameters and input concentrations. When this box is unchecked, the program uses
input concentrations as initial condition.
Display concentration profile during run
When this box is checked, the program will display the concentration profile along with the
voltammogram during the simulation. This is very helpful to understand the reaction mechanism and is
ideal for teaching purposes.
For voltammograms, the current axis scale is determined by the sensitivity scale selected under the
Parameters command. If the current axis scale is too high, the voltammogram will appear as a flat line. If
the current axis scale is too low, the data points will be scattered everywhere. However, the post-run
data display will always autoscale the voltammogram to maximize readability. The sensitivity scale can
be adjusted for the next simulation run according to the post-run display.
For concentration profiles, relative concentrations and relative distances are used. The total
concentration of all involved species is set to unity by default, and all concentrations during simulation
are scaled relative to this value. The unit distance is set to 6*sqrt(Dt) by default, where D is the diffusion
coefficient and t the total time involved in the given experiment. To change the scales for concentration
and distance from these default values, see the two sections below.
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Sim Menu
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Conc. Range
Enter the scale factor for displaying the concentration profile. The range is 0.001 - 100000, and the
default is 1.
Dist. Range
Enter the scale factor for displaying distances. The range is 0.001 - 10, and the default is 1.
Time Delay Loop
The execution time of the simulation depends on the problem you want to study and the type of
computer used. When the execution time is too short, you may not be able to visualize changes in the
concentration profile clearly. The Time Delay Loop variable allows you to slow the simulation down for
such visualization purposes, by inserting a delay of this value between the computation of two points.
The range of this parameter is from 0 to 1e6. The appropriate value will depend on the problem you want
to study and the speed of your PC.
Read/Save
You can read from/save to *.sim files that contain all the parameters needed for simulation.
On clicking the Read/Save button, the program displays an Open/Save As dialog box so you can select/
name your file.
Exp. Param
Click this button to set experimental parameters. Alternatively, use the Parameter command under
Setup menu.
The system displays the Cyclic Voltammetry Simulator Parameters dialog box so you can select the
parameters you want to use.
Kinetics
This button allows you to enter the electron transfer kinetic parameters, such as standard
heterogeneous rate constant, the standard redox potential, the charge transfer coefficient. It also allows
you to enter the forward and backward rate constant for chemical reactions.
The system displays the Potentials and Rate Constants dialog box so you can enter the kinetic
parameters.
Conc
This button allows you to enter the diffusion coefficient and concentration of all chemical species in the
system. Clicking this button displays the Concentration and Diffusion Coefficients dialog box for diffusive
systems or the Surface Concentration dialog box for adsorptive systems.
Equilibrium Command
This button allows you to view the concentration of each involved chemical species under the given
kinetic conditions. Clicking this button displays the Concentration at Equilibrium dialog box so you can
view the equilibrium state.
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Variables Command
This button allows you to specify values for other parameters, such as temperature and electrode area.
Clicking this button displays the Simulation Variables dialog box so you can enter values for the
appropriate variables.
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Sim Menu
9.1.2
215
Potentials and Rate Constants dialog box
This dialog box allows you to enter the kinetic parameters for CV simulations.
All steps of the reaction mechanism are listed on the left. Depending on the type of reaction, up to 3
parameters can be specified on the right.
For charge transfer reactions, you should enter the heterogeneous rate constant ko, the standard redox
potential Eo, and the charge transfer coefficient, alpha.
For other chemical reactions, forward and backward rate constants should be specified.
Certain kinetic parameters may be "predetermined". This is because the concentrations of n species
can be determined by n-1 reactions plus the initial conditions. It is often the case that there are more
equations than the number of species, and hence some of the equations must be linearly dependent. In
this case, The equilibrium constants of the reactions are overdetermined, and if they are all be assigned
arbitrarily, the system will never reach equilibrium.
The software will automatically detect this situation and properly assign the linearly dependent kinetic
parameters. You should put the reactions whose kinetic parameters are not well known on the bottom of
the mechanism list and let the program automatically assign their values.
If an overdetermined equilibrium constant involves a chemical reaction, the backward rate constant will
be determined by the program. You should still enter the forward rate constant.
For charge transfer reactions, the standard redox potential will be determined by the program. You
should still enter the heterogeneous rate constant and alpha.
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CH Instruments Model 900D Series
Concentration and Diffusion Coefficients dialog box
This dialog box allows you to specify the concentration and diffusion coefficients for CV simulations.
All steps of the reaction mechanism are listed in the first column. The second column lists all species in
the system. In the right two columns, you can enter the concentration and diffusion coefficient for each
species.
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Sim Menu
9.1.4
217
Surface Concentration dialog box
This dialog box allows you to specify the surface concentration for CV simulations.
All steps of the reaction mechanism are listed in the left column. The middle column lists all species in
the system. In the right column, you can enter the surface concentration for each species.
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9.1.5
CH Instruments Model 900D Series
Concentration at Equilibrium dialog box
This informational dialog box allows you to view the equilibrium concentrations computed by the CV
simulator.
All steps of the reaction mechanism are listed on the left. The equilibrium concentration of each species
is displayed on the right.
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Sim Menu
9.1.6
219
Simulation Variables dialog box
This dialog box allows you to specify selected CV simulation parameters:
Temperature
Enter the temperature in Celsius here. Both thermodynamic and kinetic parameters depend on
temperature.
Electrode Area
Enter the area of the electrode in square centimeters here. The current is proportional to the electrode
area in planar diffusion situations and surface reactions.
Capacitance
Enter the electrode double layer capacitance in microfarads here. Charging currents will be added to the
total current reported during the simulation.
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9.2
CH Instruments Model 900D Series
AC Impedance Simulator and Fitting Program
An impedance simulator is integrated into the program. To use the impedance simulator, you need to
set Technique to AC Impedance (IMP) and then use the Mechanism command to enter the equivalent
circuitry.
Once the Mechanism command has been invoked, the original toolbar will be replaced by a new one
containing symbols for components and commands.
Undo previous action.
Redo previous action.
Rearrange components.
Move components left, right, up, or down.
Clear all components.
Cut (remove) circuit element or connection.
Add resistor (Ohms).
Add capacitor (Farads).
Add inductor (Henries).
Add Warburg impedance.
Add constant phase element.
Add Cole-Cole impedance.
Add Cole-Davidson impedance.
Add Finite Length Diffusion impedance.
Add Open Finite Length Diffusion impedance.
Add Gerischer impedance.
Change simulation parameters (e.g., frequency range).
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Sim Menu
221
Open equivalent circuit file for simulation or fitting.
Save current equivalent circuit.
Run impedance simulator.
Run impedance fitting program.
Stop fitting in progress.
Exit mechanism editor simulation environment.
Circuit Editor
The equivalent circuit editor is fully graphical. To add a circuit element, click the appropriate symbol on
the toolbar and click in the main window to place the component. Double-click the component to specify
the name and value of the circuit element.
Connect two elements by moving the cursor to the left or to the right of an element. When the mouse
cursor is close to the left or right side of an element, a black dot will appear. Left-click and drag the
mouse cursor to the left or right of the other element, releasing the left mouse button when a black dot
appears on beside the other component. The two elements will now be connected.
To remove a circuit element or connection wire, left-click to select it. The color of the element or wire will
change to red. Click the Cut button on the toolbar to remove the element or wire. When an element is
deleted, all of its connections are deleted with it. You can also remove a component by left-clicking it
and dragging it out of the window.
To move elements and wires, left-click and drag, releasing the left mouse button at the desired location
in the window. Alternatively, use the Move button on the toolbar to move all components left, right, up, or
down.
To rearrange components and connection wires automatically, click the Rearrange button on the toolbar.
However, there are only four modes and they may not create an ideal diagram. You may have to redraw
the diagram manually.
To finish the equivalent circuit drawing, you need to connect to the two big dots on the left and the right
sides of the window. If you do not connect these two dots, the program will be unable to determine the
two terminals of your circuit and to start the simulation.
Other potentially useful toolbar buttons have been included to: undo or redo your actions; remove all
components and connection wires; save your equivalent circuit drawing to file and read it back later; and
change the impedance simulation parameters, such as frequency range and number of data points per
decade of frequency.
Simulation and Fitting
Please notice that the equivalent circuit you draw can be used for both simulation and fitting.
To perform a simulation, click the Sim button; the program will close the circuit editor in order to display
the simulated data on the screen. Warning: unsaved data will be erased when a new simulation starts.
Save your existing data before starting a simulation.
Data fitting requires an equivalent circuit as well as a set of impedance data, obtained from impedance
measurements or even from a preceding simulation. A poor fit may indicate an equivalent circuit that is a
poor approximation to your physical system. You may need to revise your proposed equivalent circuit to
obtain a better fit.
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The fitting program has known limitations. Sometimes, a poor fit will be obtained even with a known
(simulated) data set. Results may also depend on the initial values of the components. If you experience
problems, please send the data to [email protected] We will try to study and improve it, but
cannot guarantee better results. Efficient fitting algorithms are difficult and complicated to obtain.
Click the Fit button on the toolbar to start the fitting process. During fitting, the elapsed time, fitting error,
and evolution of circuit element parameters will be displayed. The fitting process is complete when the
component values have converged; the resulting values value of circuit elements as well as fitting error
will be displayed. To stop the fitting process, click the Exit button on the toolbar. The original and fitted
data will be overlaid and displayed.
To exit the circuit editor and return to the main program, click the Exit button.
Notes
Before you run the fitting program, make sure the instrument is correctly connected to your PC, e.g. by
running the Self Test command. The program will verify that your instrument model is supported. This
check only needs to be performed once after the program is started. After the first fit, you do not need to
have the instrument connected anymore.
When carrying out impedance simulation and fitting, do not run other techniques or read data files other
than impedance measurements. Otherwise the circuit editor may not function correctly.
Circuit Element Notation and Ranges
Circuit Element
Resistor
Capacitor
Inductor
Warburg Impedance
Constant Phase
Cole-Cole
Cole-Davidson
Finite Layer Diffusion
Abbrev.
R
C
L
W
Q
CC
CD
FD
Open Finite Layer
Diffusion
OFD
Gerischer Impedance GI
Units
Ohm
Farad
Henry
Siemens sec 1/2
Siemens sec n
Ohm
Ohm
Siemens sec 1/2
Range
0.001 to 1e12
1e-12 to 1
1e-12 to 1
1e-6 to 1
1e-12 to 1000
0.001 to 1e12
0.001 to 1e12
Yo = 1e-12 to 1e12
Siemens sec
1/2
d/v D = 1e-6 to 1000
Yo = 1e-12 to 1e12
Siemens sec
1/2
d/v D = 1e-6 to 1000
Yo = 1e-12 to 1e12
k = 1e-12 to 1e12
Circuit Element Properties
Element
R (resistor)
Impedance
ZR = R
Conductance
YR = 1/R
C (capacitor)
ZC = -j/ C
YC = j C
L (inductor)
ZL = j L
YL = -j/ L
-1/2
W (Warburg)
ZW = (j )
Q (phase)
ZQ = (j )-n/Yo
CC (Cole-Cole)
ZCC = R / [1+(j
CD (Cole-
ZCD = R / (1+j
= /2
1/2
/Yo
YW = (j )
= - /2
Yo
YQ = (j )n Yo
) ] YCC = [1+(j
)
Phase
= 0 (frequency-independent)
YCD = (1+j
= /4
= n /2, 0 < n < 1
) ] / R tan
) /R
= ( ) sin(
/2) / [1+( ) cos(
/2)]
tan ( / ) =
© 2014 CH Instruments, Inc.
Sim Menu
Davidson)
FD (Finite Layer
Diffusion)
ZFD = 1/YFD
OFD (Open Finite ZOFD = 1/YOFD
Layer Diffusion)
GI (Gerischer
Impedance)
ZGI = 1/YGI
YFD = Yo sqrt(j )
tan ( ) = arg (YFD )
tanh[ sqrt(j /D)]
YOFD = Yo sqrt(j )
tan ( ) = arg (YOFD )
223
coth[ sqrt(j /D)]
YGI = Yo sqrt(k + j ) tan ( ) = arg (YGI )
For more information, refer to J. R. Macdonald, Ann. Biomed. Eng., 20, 289-305 (1992) or "Impedance
Spectroscopy", E. Barsoukov and J. R. Macdonald, Wiley, Hoboken, 1987 (1st ed), 2005 (2nd ed).
© 2014 CH Instruments, Inc.
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9.3
CH Instruments Model 900D Series
CV Simulate command
Use this command to generate simulated CV data.
The reaction mechanism, concentrations, kinetic parameters, and experimental parameters must be first
set with the Mechanism command before the simulation is run.
In order to do simulation, make sure the instrument is correctly connected to your PC, e.g. by running
the Self Test command. The program will check for the proper instrument model. It only needs to check
once after the program is started. After the first fit, you do not need to have the instrument connected
anymore.
You can copy the screen graphics to the clipboard during the simulation.
© 2014 CH Instruments, Inc.
Sim Menu
9.4
225
CV Fitting command
Use this command to fit parameters to existing CV data, leveraging our built-in CV simulator to evaluate
the fit (select models only).
Before you run the fitting program, make sure the instrument is correctly connected to your PC, e.g. by
running the Self Test command. The program will verify that your instrument model is supported. This
check only needs to be performed once after the program is started. After the first fit, you do not need to
have the instrument connected anymore.
First open the CV data file you want to fit. This can be either experimental or simulated data. Using the
CV Fitting command will then open the CV reaction mechanism dialog box discussed in a previous
section. A judicious choice of mechanism is critical here--the numerical fitting algorithm could find an
excellent fit to an incorrect mechanism, yielding unmeaningful and misleading results. The system must
be specified as diffusive or a surface reaction, but kinetic parameters need not be entered.
Click OK in the Digital Simulation dialog box to bring up the CV Fitting Parameter dialog box.
This dialog box allows you to specify parameters for the CV Fitting program.
The previously selected reaction mechanism and its associated potentials and rate constants will be
shown. You do not need to enter kinetic parameters. A well chosen initial value may reduce the time
needed for fitting, although this is not required. You can also assign and fix any kinetic parameters
whose correct values are known beforehand. Checking Fix for any variable will prevent its value from
being changed during the fitting process, reducing the total number of unknown variables and thus the
time needed for fitting.
The initial values for the fitting potential range is determined automatically from the peak potentials, but
the positive and negative limits can also be specified manually in the Fit_eh(v) and Fit_el(v) fields,
respectively.
The fitting procedure will generate a fitted curve over the entire potential range, but the goodness of fit will
only be measured on the Fitting Potential Range subinterval. This is because toward more extreme
potentials there tend to be significant contributions from residual or background current, which are
insensitive to changes in the kinetic parameters and difficult to fit accurately. The potential subinterval
near the peak currents tend to be more sensitive to the kinetic parameters.
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CH Instruments Model 900D Series
Since charging current can also make a significant contribution to CV data, the double layer capacitance
is also available as a variable or constant.
Our algorithm minimizes the absolute error, defined as
sqrt [
i
(Fi - Ei)^2 ] / N,
where the Fi are fitted data points, Ei are your input data points, and N is the total number of data points.
Absolute instead of relative error is used to avoid overweighting points for which the current nearly
vanishes.
The Skip parameter allows you to to omit data points from the fitting procedure, which can greatly
reduce the fitting time. The Error parameter is the desired error threshold, below which the fitting
procedure will end.
Click OK to start the fitting procedure.
The fitting potential range will be bracketed graphically, with the fitted data plotted in green and your
input data plotted in red. Fitting error and the time elapsed are also displayed in the top left. The fitting
process will end when the specified Error is reached; alternatively, it can be terminated at any time by
clicking the Stop button or by pressing the Esc key. The resulting fitted kinetic parameters will be then
be displayed.
© 2014 CH Instruments, Inc.
View Menu
Chapter 10 View Menu
The View menu offers the following commands:
Data Information
Data Listing
Equations
Clock
Toolbar
Status Bar
© 2014 CH Instruments, Inc.
View data information.
View current data as a text list.
View equations related to the selected technique.
View current date and time.
Shows or hides the toolbar.
Shows or hides the status bar.
227
228
10.1
CH Instruments Model 900D Series
Data Information command
This command opens the Data Information dialog box.
Use this command to view the information of the currently active data, including the date and time of the
experiment, data source, and type of data processing. You can also enter your own notes about the
experiment.
The Data Information command presents this dialog box.
Filename
This non-editable box displays the name of the file containing the currently active data. If the data have
not been stored, the filename is "Unsaved".
Data Source
This box will read either "Experiment" or "Simulated."
Model
This box displays the instrument model with which the data were acquired.
Date
This box displays the date that the data were acquired.
Time
© 2014 CH Instruments, Inc.
View Menu
229
This box displays the time that the data were acquired.
Data Proc Performed
This list box displays what types of data processing have been previously performed on the data, if
applicable. If several types of data processing have been performed, multiple items will be highlighted.
Header
This box displays the optional data plot header (title).
Note
This box displays user-defined notes, and is best suited for a brief description of the purpose and
conditions of the experiment/simulation.
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10.2
CH Instruments Model 900D Series
Data Listing command
This command opens the Data List dialog box.
The format of the list can be altered by the Text File Format command under the File menu.
The Data List command presents this dialog box.
This dialog box lists the experimental conditions, results, and numerical values of the currently active
data, with scroll bars if necessary. If the list is too long, the later part of the data will be truncated.
© 2014 CH Instruments, Inc.
View Menu
10.3
231
Equations command
This command opens the help browser to view equations related to the electrochemical technique
currently invoked.
The following is a list of available equations. For more details about the equations and how to use them,
please refer to "Electrochemical Methods", A.J. Bard and L.R. Faulkner, Wiley, New York, 1980 (1st
ed), 2001 (2nd ed).
Equations
General equations
Symbols and Units
Linear Sweep Voltammetry (LSV) and Cyclic Voltammetry (CV)
Staircase Voltammetry (SCV)
Tafel Plot (TAFEL)
Chronoamperometry (CA)
Chronocoulometry (CC)
Differential Pulse Voltammetry (DPV)
Normal Pulse Voltammetry (NPV)
Square Wave Voltammetry (SWV)
AC Voltammetry (ACV)
Second Harmonic A.C. Voltammetry (SHACV)
Amperometric Curve (i-t)
Bulk Electrolysis with Coulometry (BE)
Hydrodynamic Modulation Voltammetry (HMV)
AC Impedance (IMP)
Chronopotentiometry (CP)
Potentiometric Stripping Analysis (PSA)
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10.4
CH Instruments Model 900D Series
Clock command
This command opens the Clock dialog box.
Use this command to view the current date and time, which are refreshed constantly.
The Clock command presents this dialog box, which displays the current system date and time.
© 2014 CH Instruments, Inc.
View Menu
10.5
233
Toolbar command
Use this command to display and hide the toolbar, which includes buttons for some of the most
common commands in the program, such as File Open. A checkmark appears next to the menu item
when the toolbar is displayed.
The toolbar is displayed across the top of the application window, below the menu bar, as shown below.
The toolbar is displayed across the top of the application window, below the menu bar. The toolbar
provides quick mouse access to many tools used in the program.
To hide or display the toolbar, click Toolbar from the View menu.
Create a new document.
Open an existing document using the Open dialog box.
Save the active document
Print the active document.
Select one of many electrochemical techniques.
Choose experimental parameters.
Start experiment.
Pause experiment.
Stop experiment.
Reverse CV scan direction.
Zero current.
Set and test iR compensation.
Set potential and current filters.
Set purge, stir, cleaning, and other cell conditions.
Calibrate and control SECM probe.
Plot current data graphically.
Increase zoom in graphics mode.
Report results manually.
Define peak or wave parameters.
Adjust graphics options.
Set color and legend in graphics.
Set caption font in graphics.
Copy graphics to clipboard.
Data smoothing.
Compute derivative.
Compute semi-integral and semi-derivative.
View current data as text.
View SECM probe status.
Enter context-sensitive help mode (Shift + F1).
© 2014 CH Instruments, Inc.
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10.6
CH Instruments Model 900D Series
Add or Remove Buttons command
This command opens the Customize Toolbar dialog box. It is available as a drop-down arrow on the
default toolbar.
There are several ways to add, remove, or reorder buttons on your toolbar. For maximum convenience,
use method 1 to reorder or remove buttons, method 2 to add buttons in specified locations, and method
3 to add buttons to the right end of your toolbar. Use the Reset button in the Customize dialog box to
restore the default toolbar buttons (and menus, if applicable).
1. In the main program window, while holding down the Alt key you can click on any button and drag it to
a new position, or even drag it off the toolbar altogether to remove it. To add buttons, simply drag them
from the Customize Toolbar dialog box onto the toolbar (direct drag-and-drop and user-customizable
menus require Windows XP or higher and the corresponding edition of our software).
2. In the Customize Toolbar dialog box, drag and drop buttons to conveniently add, remove, or reorder
them. That is, click on an item in the list of "Current toolbar buttons" and drag it around in the
"Current" list to change its position, or drag it into the list of "Available toolbar buttons" to remove it
from your toolbar. Similarly, buttons can be added from the "Available" list by dragging them into the
"Current" list.
3. In the Customize Toolbar dialog box, double-click on a button in the list of "Available toolbar buttons"
to add it to the toolbar. However, this will add it to the bottom of the list, and to change its position
you must either drag it vertically or click the Move Up/Down button. Similarly, double-click on a button
in the list of "Current toolbar buttons" to remove it from your toolbar; it will be automatically sorted into
the "Available" list.
4. In the Customize Toolbar dialog box, click on the corresponding buttons to perform the desired
operations. The Reset button will restore the default toolbar.
Caveats
If your toolbar displays improperly, please restart your application.
This command is currently not compatible with the AC Impedance simulator.
Toolbar settings are saved locally in your ini file; as an alternative to clicking the Reset button, simply
delete your ini file to restore the default toolbar. Beware that manually editing the ini file may result in
unexpected behavior.
© 2014 CH Instruments, Inc.
View Menu
10.7
235
Status Bar command
Use this command to display and hide the status bar, which describes the action to be executed by the
selected menu item or pressed toolbar button, and keyboard latch state. A checkmark appears next to
the menu item when the status bar is displayed.
The status bar is displayed at the bottom of the program window. To display or hide the status bar, use
the Status Bar command in the View menu.
The left area of the status bar describes actions of menu items as you use the arrow keys to navigate
through menus. This area similarly shows messages that describe the actions of toolbar buttons as you
press them, before releasing them. If after viewing the description of the toolbar button command you
wish not to execute the command, then release the mouse button while the pointer is off the toolbar
button.
The right area of the status bar indicates the currently active technique.
© 2014 CH Instruments, Inc.
Help Menu
237
Chapter 11 Help Menu
The Help menu offers the following commands, which provide you assistance with this application:
Help Topics
About
© 2014 CH Instruments, Inc.
Offers you an index to topics on which you can get help.
Displays the version number of this application.
238
11.1
CH Instruments Model 900D Series
Help Topics command
Use this command to display the opening screen of help. From the opening screen, you can jump to
step-by-step instructions for using the program and various types of reference information.
Once you open help, you can click the Home button whenever you want to return to the opening screen.
Context-sensitive help is available for the pull-down menus and the buttons on the toolbar. Press
Shift+F1 to activate context-sensitive help (the mouse pointer will change to an arrow and question
mark), and click on a menu command, toolbar button, or other part of the application window to learn
more about it.
© 2014 CH Instruments, Inc.
Help Menu
11.2
239
Old Help command
Check this item to enable legacy .hlp file context-sensitive help (if available). Please note that such .hlp
files are no longer kept up to date.
© 2014 CH Instruments, Inc.
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11.3
CH Instruments Model 900D Series
About command
Use this command to display the copyright notice, version number, software revision date, and
manufacturer's contact information.
© 2014 CH Instruments, Inc.
Appendix
241
Chapter 12 Appendix
This chapter contains technical details, safety information, and an overview of our full line of
electrochemical instrumentation. More information about the latter is also available on our website at
www.chinstruments.com.
Cables and Connections
Firmware Update Instructions
Troubleshooting
Maintenance and Service
Limited Warranty
Safety
Abbreviations
Model 400C Series Time-Resolved Electrochemical Quartz Crystal Microbalance
Model 600E Series Electrochemical Analyzer
Model 700E Series Bipotentiostat
Model 800D Series Electrochemical Detector
Model 920D Scanning Electrochemical Microscope
Model 1000C Series Multi-Potentiostat
Model 1100C Power Potentiostat / Galvanostat
Model 1200B Handheld Potentiostat / Bipotentiostat
Pico-Liter Solution Dispenser
Picoamp Booster/Faraday Cage and Multiplexer
Amp Booster and Liquid/Liquid Interface Adapter
Accessories
© 2014 CH Instruments, Inc.
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12.1
CH Instruments Model 900D Series
Cables and Connections
Electrode connection (Video connector)
Pin
Function
1
Working electrode
2
Sensing electrode*
3
Second working electrode
4
Reference Electrode
5
Counter electrode
6
Analog Ground
Color (if applicable)
Green
Black
Yellow
White
Red
* This electrode is used for 4-electrode configuration, which can be used for liquid/liquid interface
measurements. In this case, the red and white clips are respectively connected to the counter and
reference electrodes in phase I, and the green and black clips are respectively connected to the counter
and reference electrodes of phase II.
The 4-electrode configuration also helps to eliminate contact resistance (due to clips, connectors, and
switching relay) and the resistance of circuitry traces, which is very important for large current (> 100
mA) measurements and low impedance cells (< 1 ohm). However, some instruments have a maximum
current of 10 mA or lower. It is therefore not necessary to employ 4-electrode configuration in non-L/L
measurements in these instances.
To use 4-electrode configuration, please check the "4-Electrode" option using the Cell command under
the Control menu. If you are using the 4-electrode configuration to eliminate contact resistance, you
should connect the sensing electrode together with the working electrode.
When not using 4-electrode configuration, please make sure that the "4-Electrode" box in the Cell
Control dialog box is unchecked. Otherwise noise and other problems may occur.
When using 3-electrode configuration, please leave the Sensing electrode unconnected.
RDE Control Connection (Banana jack s)
Red
Signal
Black
Analog Ground
Signal Output on Rear Panel (9-pin D connector)
1
Current 1 Output
2
Current 2 Output (bipotentiostat)
3
Potential Output
4
External Potential Input**
5
External Signal Input*
6
Ground
7
Ground
8
Ground
9
Ground
* The input voltage range is 10 V, and the input impedance of the input stage is 10K ohms. For signals
with high voltages, a resistor divider should be used. For signals with a small voltage range (< 0.1 V), it
is possible to amplify the signal by a factor of 10 or 100; please contact [email protected] for
details.
** The external potential input is disabled by default. To enable it, you need to change a jumper setting
inside the instrument. Please contact [email protected] for details.
© 2014 CH Instruments, Inc.
Appendix
243
Com Port connection (DB-25 connector)
Pin
Function
2
Receive
3
Transmit
7
Digital Ground
Cell Control connection (DB-25 connector)
Pin
Function
1
2
Stepper motor control line 1
3
Stepper motor control line 2
4
Analog Ground
5
-15 V (< 20 mA load)
6
+5 V (< 100 mA load)
7
Digital Ground
8
Stir (active level can be set in Cell Control)
9
Knock (active low pulse)
10
External Device Sense 1
11
External Device Sense 2
12
External Device Control 1
13
External Device Sense 3 (external trigger input, TTL signal, active low)
14
Stepper motor control line
15
Piezo positioner control line
16
Piezo positioner control line
17
+15 V (< 20 mA load)
18
Piezo positioner control line
19
External Device Control 2
20
External Device Control 3
21
Purge (active low level)
22
23
External Device Control 4
24
External Device Control 5
25
Reserved
The Cell Control port can be used to control stir, knock, and purge. Please check the manual of your cell
stand for compatibility. Customized jumper settings or connection cables might be needed.
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12.2
CH Instruments Model 900D Series
Firmware Update Instructions
The instrument is controlled using software on the PC side, and updates will often be as straightforward
as replacing chi####.exe with a newer version. Occasionally, however, the instrument firmware will also
need to be updated.
The instrument firmware is now stored in flash memory, allowing it to be distributed electronically rather
than through the inconvenient mailing of an EPROM chip. Software and firmware are both available from
[email protected] Software installation is described in Chapter 2 of this User Manual. Firmware
updates are distributed in the form of a hexadecimal file (chi####.hex, where #### is the model number).
To initiate a firmware update, use the Update Instrument Program command under the File menu to bring
up the following dialog box:
Click the Browse button to select the appropriate hex file, or type its name and full path in the Filename
field.
Click the Update button to upload the hex file to the instrument flash memory. During the upload, please
be patient and wait. Please do not activate any other program, and as when updating the firmware/BIOS
of any piece of electronics, do not interrupt power to either the PC or the instrument. Any of these
actions could cause the upload to fail and corrupt the flash memory, rendering the instrument unusable
short of force programming back at the factory. Please contact CH Instruments, Inc. at
[email protected] if this event should occur.
If the upload does not succeed, you will get an error message. In this case, turn the instrument off for 510 seconds, then turn it back on. You may need to exit and restart the PC program before trying again.
If the upload is successful, you will get a confirmation message. The updated instrument is now ready to
use.
© 2014 CH Instruments, Inc.
Appendix
12.3
245
Troubleshooting
Problem
Link failed
Unresponsive
mouse
Possible Cause
Power is not on
Cable is disconnect
Faulty cable
COM port setting does not match
port in use
Computer problem
Static discharge
Lengthy computation process
Communication failed
Windows application
error
Hardware test error
No current response Electrode leads disconnected or
broken
Noisy data
Unreliable data transfer
Data out of range
Overflow warning
during experiment
Y-axis title rotated
incorrectly
Unreasonable
default conditions
Simulation program
does not run
Action
Power on the instrument
Connect the instrument to the computer
Check and change cable
Change settings using System command
under Setup menu
Remove network/modem cards if present; if
problem persists, try other computers
Reset instrument and computer
Wait for computation to complete
Reset instrument and computer
Restart program or reset the computer
Repeat hardware test and report error
message to [email protected]
Check electrode leads
If data reading exceeds 10 × sensitivity
scale, the problem could be related to the
COM port; remove network/modem cards if
present or try other computers
Reference electrode impedance too Check for trapped air bubble at reference
high
electrode tip; use reference electrode with
Vycor tip
Electrically noisy environment
Use Faraday cage; see Useful Tips section
in Chapter 2
Instability of potentiostat due to large Use Cell command under Control menu to
double layer capacitance
manually turn on stabilizing capacitor
Weak signal
Increase sensitivity scale; adjust filters
Computer problem
Remove network/modem cards if present or
try other computers
Sensitivity scale too high
Lower sensitivity scale
Hardware problem
Use Hardware Test command under Setup
menu to test hardware
Sensitivity scale too high
Lower sensitivity scale
Printer driver incompatibility
Incompatible configuration (.cfg or .
ini) file
Instrument not found
Use Font command under Graphics menu to
toggle Y-axis title rotation
Delete old configuration files; new files will be
generated automatically
Connect and power on the instrument
User input mechanism unavailable for Use a pre-defined mechanism
this instrument model
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12.4
CH Instruments Model 900D Series
Maintenance and Service
The recommended operating temperature is 15 - 28°C.
Since the instrument is a sophisticated piece of equipment, you should not try to service it yourself. If it
is not working properly, please run the hardware test and contact the factory for service.
© 2014 CH Instruments, Inc.
Appendix
12.5
247
Limited Warranty
This CH Instruments product is warranted against defects in workmanship and material. If any failure
resulting from a defect of workmanship or material shall occur under normal use within one year from the
date of purchase shown on the purchase receipt, CH Instruments, Inc. will, at its option, either repair the
defective product without charge for parts and labor, or provide a replacement in exchange for the
defective product.
In order to obtain service under this warranty, the customer must notify CH Instruments, Inc. before the
expiration of the warranty period and make arrangements for service. The customer shall be responsible
for packing and shipping the defective product with prepaid shipping charges. CH Instruments, Inc. will
pay for return shipping of the repaired or replacement product to the customer within the United States.
The customer shall be responsible for all shipping charges, duties, taxes, and other charges for products
sent outside of the United States.
Warranty service does not cover failures caused by misuse, accident, modification, unsuitable physical
or operating environment, improper maintenance, or service of the product by unauthorized personnel.
In no event shall CH Instruments, Inc. be liable or in any way responsible for any lost profits, lost
savings, incidental, or other financial consequential damages. This is true even if you advise CH
Instruments, Inc. of the possibility of such damages.
© 2014 CH Instruments, Inc.
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12.6
CH Instruments Model 900D Series
Safety
Section 1: LVD Notes for manual safety issues and protection of instrument against damage
1. The unit described in this manual is designed to be operated by trained personnel with a reasonable
background knowledge of electrochemistry. Any adjustments, maintenance, or repairs must be carried
out as defined by this manual (please refer to Appendix sections above) by a qualified person aware of
the hazards involved.
2. (a) It is essential that operating personnel follow safe working procedures, in addition to the detailed
instructions specified in this manual.
2. (b) The instrument should be placed in a position where the likelihood of the ingress of a chemical
spill is kept to an absolute minimum. Efforts should also be made to avoid contact of the instrument
with, for instance, corrosive vapours. The electrochemical cell should not be placed on top of the unit due
to the risk of leakage and the possibility of the cell contents entering the instrument. If chemicals do
enter the unit, switch it off immediately and contact the nearest dealer/CH Instruments, Inc. (contact
details at the front of this manual). Routine cleaning of the chassis of the instrument is not necessary. A
spill onto the outer casing that does not enter the instrument should be wiped off with a dry cloth,
making sure to wipe away from any instrument connections. Likewise, the PC used to operate the
instrument should be protected from possible exposure to chemicals.
2. (c) Despite the customer's best efforts, corrosion of the electrode leads can occur. This condition is
best diagnosed by running a CV from -1 V to +1 V on a 1 M Ohm resistor, with sensitivity set to 1e-6.
An Ohmic plot through the origin should be obtained, with maximum current of ±1 µA. Working contacts
(green and black) are connected to one side of the resistor and counter (aux) and reference (red and
white) to the other. Noticeable divergence from this behavior (i.e., linearity through the origin) may
suggest faulty leads.
2. (d) Erroneous data/behavior in an actual electrochemical experiment may be due to factors such as
faulty cell connections, poor reference electrode contact, or poor condition of the working electrode.
Reference and working electrodes are consumable items and are readily available from CH Instruments,
Inc. or your local dealer (see Appendix for a description of the range of accessories available). When a
customer uses his/her own electrodes, it is recommended that experimental data be compared against
known standards from time to time.
3. The cover of the instrument should only be removed by qualified personnel at the direction of CH
Instruments, Inc..
4. Users should always refer to the health and safety data supplied with any chemicals used. Generally
accepted laboratory procedures for the safe handling of chemicals should always be employed.
5. Evidence of any fault condition should immediately be reported to CH Instruments, Inc. or the local
distributor as applicable. Hardware faults are usually diagnosed through the instrument's own self test
procedure (see Troubleshooting in the Appendix).
6. As the instrument requires a data connection to a PC, we recommend that sufficient space (at least 2
m of linear bench) is set aside in order to avoid cluttering the work area and to ensure easy access to
the cell. There should be enough free space around the vents and fan exhaust of the instrument to
prevent overheating.
7. Connections to the cell by crocodile clips should be made in such a way as to avoid shorting of the
contacts.
© 2014 CH Instruments, Inc.
Appendix
249
Section 2. Power configuration
On unpacking the instrument the presence of the following should be noted.
1. Mains cable
2. Cell Lead
3. User Manual
4. Optional accessories if ordered (cells, electrodes, etc.)
The instrument is designed to operate at 110V or 220 V (+/-20%) AC power @ 50/60 Hz. Please check
the rear panel label for its input voltage setting. If an incorrect AC voltage is connected, the fuse will blow
and the instrument may be damaged.
The correct voltage and line frequency for your region have been set at our factory prior to shipment.
The standard 2 meter (or 6 foot) mains cable is fitted with an IEC type connector which can be plugged
directly into the power input on the rear panel of your instrument. The mains fuse (250V L 0.4A) is
housed within the power socket. When replacing the fuse, the user should fully disconnect the
instrument from the power supply.
In the event of repeat fuse failure, the user should consult CH Instruments, Inc. before proceeding further.
The unit should be placed within 1.5 m of a grounded mains power supply.
When the instrument is powered on, the indicator light on the front panel will be illuminated.
Rear panel of instrument
1.
2.
3.
4.
Power switch
On/off switch of unit
Fuse
State fuse value here
Power input socket
IEC type connection socket for mains cable
Cooling fan
Fuse rating = 0.8 A for 110V AC input, 0.4 A for 230V AC input
Power cord rating = 15 A for 110V AC input, 10 A for 230V AC input
All other features are clearly labeled on the rear panel itself.
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CH Instruments Model 900D Series
© 2014 CH Instruments, Inc.
Appendix
12.7
Abbreviations of Electrochemical Techniques
ACV
BE
CA
CC
CP
CPCR
CV
DDPA
DNPV
DPA
DPV
ECN
FTACV
HMV
IMP
IMP-t
IMP-E
IPAD
ISTEP
i-t
LSV
NPV
OCPT
PSA
QCM
SCV
SHACV
SSF
SWV
TAFEL
TPA
AC Voltammetry (including phase-selective)
Bulk Electrolysis with Coulometry
Chronoamperometry
Chronocoulometry
Chronopotentiometry
Chronopotentiometry with Current Ramp
Cyclic Voltammetry
Double Differential Pulse Amperometry
Differential Normal Pulse Voltammetry
Differential Pulse Amperometry
Differential Pulse Voltammetry
Electrochemical Noise Measurement
Fourier Transform AC Voltammetry
Hydrodynamic Modulation Voltammetry
Impedance Spectroscopy
Impedance - Time
Impedance - Potential
Integrated Pulse Amperometric Detection
Multi-Current Steps
Amperometric i-t Curve
Linear Sweep Voltammetry
Normal Pulse Voltammetry
Open Circuit Potential - Time
Potentiometric Stripping Analysis
Quartz Crystal Microbalance
Staircase Voltammetry
Second Harmonic AC Voltammetry (including phase-selective)
Sweep-Step Functions
Square Wave Voltammetry
Tafel Plot
Triple Pulse Amperometry
© 2014 CH Instruments, Inc.
251
252
12.8
CH Instruments Model 900D Series
Model 400C Series Time-Resolved Electrochemical Quartz
Crystal Microbalance
The quartz crystal microbalance (QCM) is a variant of acoustic w ave microsensors that are capable of ultrasensitive mass
measurements. For example, using our crystal, w hich has a fundamental frequency of 7.995 MHz, a net change of 1 Hz in
oscillation frequency corresponds to 1.34 ng of mass adsorbed/desorbed onto/from a crystal surface of area of 0.196 cm2.
QCM in conjuction w ith electrochemistry (EQCM) has been w idely employed for the determination of deposited metals,
studies of ion-transport processes in polymer films, biosensor development, and investigations of the adsorption/desorption
kinetics of adsorbate molecules. In EQCM experiments, measurements of various electrochemical parameters, such as
potential, current, and charge at the w orking electrode, are conducted simultaneously w ith the acquisition of the
corresponding frequency and resistance changes, using the experimental setup show n in the Figure below . For any model
in the 400C series, application of a specific potential w aveform (e.g., triangular potential w aveform for cyclic voltammetric
experiments), current measurement, and frequency counting are carried out w ith a potentiostat/frequency counter, w hich is
in turn controlled by a personal computer.
The 400C series contains a quartz crystal oscillator, a frequency counter, a fast digital function generator, a high-resolution
and high-speed data acquisition circuitry, a potentiostat, and a galvanostat (Model 440C only). The QCM is integrated w ith the
potentiostat and galvanostat to facilitate simple and convenient EQCM studies. Instead of measuring the frequency directly,
the 400C series uses a time-resolved mode as follow s. The observed frequency of the QCM is subtracted from a standard
reference frequency, and the resulting difference is measured by a reciprocal technique, greatly reducing the required
sampling time and yielding much better time resolution for the QCM signal. With direct counting, a QCM frequency resolution of
1 Hz requires 1 second of sampling time, 0.1 Hz resolution requires 10 seconds, etc. In contrast, our time-resolved mode
allow s the QCM signal to be measured in milliseconds w ith much better resolution. QCM data can be recorded for a scan rate
of 1 V/s or low er.
The EQCM cell consists of three round Teflon pieces (see Figure below ). The total height is 37 mm w ith a diameter of 35 mm.
The top piece is the cell top, w hich holds the reference and counter electrodes. There are also tw o 2 mm holes for manual
purging. The center piece is the solution cell, and the bottom piece is for mounting purposes. Four screw s are used to tighten
an O-ring seal betw een the bottom and center pieces, w ith the quartz crystal sandw iched betw een them. The diameter of
the quartz crystal is 13.7 mm. The gold electrode diameter is 5.1 mm.
Specifications
Potentiostat
Galvanostat (Model 440C)
2, 3, or 4-electrode configuration
Potential range: -10 to 10 V
Applied potential accuracy: ±1 mV, ±0.02% of scale
Potentiostat rise time: < 2 µs
Compliance voltage: ±12 V
Maximum current: ±250 mA continuous, ±350 mA peak
Reference electrode input impedance: 10-12 ohm
Sensitivity scale: 10-12 - 0.1 A/V in 12 ranges
Input bias current: < 50 pA
Current resolution: 0.0015% of current range, min. 0.3 fA
Minimum potential increment in CV: 100 µV
Fast w aveform update: 10 MHz @ 16-bit
Data acquisition: 16 bit @ 1 MHz
External signal recording channel
QCM Frequency resolution: < 0.1 Hz
QCM maximum sampling rate: 1 kHz
Automatic and manual iR compensation
CV and LSV scan rate: 0.000001 to 5000 V/s
Potential increment during scan: 0.1 mV @ 1000 V/s
CA and CC pulse w idth: 0.0001 to 1000 sec
CA and CC minimum sample interval: 1 µs
CA and CC Steps: 320
DPV and NPV pulse w idth: 0.0001 to 10 sec
SWV frequency: 1 Hz to 100 kHz
i-t sample interval: minimum 1 µs
ACV frequency: 0.1 Hz to 10 kHz
SHACV frequency: 0.1 Hz to 5 kHz
IMP frequency: 0.00001 Hz to 10 kHz
Low -pass signal filters, automatic and manual setting
Potential and current analog output
RDE rotation control output: 0 - 10 V (selected models)
CV simulation and fitting program
Cell control: purge, stir, knock
Data length: 128K - 4096K selectable
Chassis dimensions: 14.25"(W) × 9.25"(D) × 4.75"(H)
Oscillator box (external): 4.75"(L) × 2.6"(W) × 1.55"(H)
Weight: 12 lb.
© 2014 CH Instruments, Inc.
Appendix
253
430C
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440C
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450C
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Techniques for Model 400C Series
Technique
Cyclic Voltammetry (CV)
Linear Sw eep Voltammetry (LSV) &
Staircase Voltammetry (SCV) #,&
400C
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410C
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420C
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Tafel Plot (TAFEL)
Chronoamperometry (CA)
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Chronocoulometry (CC)
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Differential Pulse Amperometry (DPA)
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Double Differential Pulse Amperometry (DDPA)
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Hydrodynamic Modulation Voltammetry (HMV)
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Sw eep-Step Functions (SSF)
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Multi-Potential Steps (STEP)
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Differential Pulse Voltammetry (DPV)
Normal Pulse Voltammetry (NPV)
#,&
#,&
Differential Normal Pulse Voltammetry (DNPV)
Square Wave Voltammetry (SWV)
AC Voltammetry (ACV)
#,&
&
•
#,&,$
2nd Harmonic AC Voltammetry (SHACV)
#,&,$
Amperometric I-t Curve (I-t)
Triple Pulse Amperometry (TPA)
Bulk Electrolysis w ith Coulometry (BE)
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AC Impedance (IMP)
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Impedance - Time (IMPT)
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Impedance - Potential (IMPE)
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Chronopotentiometry (CP)
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Chronopotentiometry w ith Current Ramp (CPCR)
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Potentiometric Stripping Analysis (PSA)
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Open Circuit Potential - Time (OCPT)
Quartz Crystal Microbalance (QCM)
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Galvanostat
RDE control (0-10V output)
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Full version of CV simulator
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Limited version of CV simulator
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Impedance simulation and fitting program
iR Compensation
#
Corresponding polarographic mode can be performed.
Corresponding stripping mode can be performed.
$ Phase-selective data are available.
&
© 2014 CH Instruments, Inc.
•
•
254
CH Instruments Model 900D Series
EQCM setup
© 2014 CH Instruments, Inc.
Appendix
12.9
255
Model 600E Series Electrochemical Analyzer Techniques
Technique
CV
LSV &
SCV #,&
TAFEL
CA
CC
DPV #,&
NPV #,&
DNPV #,&
SWV &
ACV #,&,$
SHACV #,&,$
FTACV
i-t
DPA
DDPA
TPA
IPAD
BE
HMV
SSF
STEP
IMP
IMP-t
IMP-E
CP
CPCR
ISTEP
PSA
ECN
OCPT
600E
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602E
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604E
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606E
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608E
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610E
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620E
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630E
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650E
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#
Corresponding polarographic mode can be performed.
&
Corresponding stripping mode can be performed.
$
Phase-selective data are available.
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660E
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Dynamic Range of Selected Experimental Parameters
Parameter
Potential (V)
Current (A)
Sensitivity (A/V)
Sampling Rate
Scan rate (V/s)
Pulse w idth (sec)
Pulse w idth (sec)
Sampling interval (sec)
Frequency (Hz)
Frequency (Hz)
Frequency (Hz)
Frequency (Hz)
© 2014 CH Instruments, Inc.
Range
-10 to +10
0 to ±0.25 (peak ±0.35)
10-12 to 0.1
1 MHz at 16-bit resolution
0.000001 to 10000
0.0001 to 1000
0.001 to 10
0.0001 to 10
1 to 100000
0.1 to 10000
0.1 to 5000
0.00001 to 1000000
Techniques
CV, LSV
CA, CC
DPV, NPV
DPV, NPV
SWV
ACV
SHACV
IMP
256
CH Instruments Model 900D Series
12.10 Model 700E Series Bipotentiostat Techniques
Technique
CV
LSV &
SCV #,&
TAFEL
CA
CC
DPV #,&
NPV #,&
DNPV #,&
SWV &
ACV #,&,$
SHACV #,&,$
FTACV
i-t
DPA
DDPA
TPA
IPAD
BE
HMV
SSF
STEP
IMP
IMP-t
IMP-E
CP
CPCR
ISTEP
PSA
ECN
OCPT
700E
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701E
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710E
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720E
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730E
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750E
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#
Corresponding polarographic mode can be performed.
&
Corresponding stripping mode can be performed.
$
Phase-selective data are available.
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760E
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Dynamic Range of Selected Experimental Parameters
Parameters
Potential (V)
-10 to +10
Range
Current (A)
0 to ±0.25 (one channel only)
Current (A)
0 to ±0.125 (dual channel)
Sensitivity (A/V)
10-12 to 0.1 (both channels)
Sampling Rate
1 MHz at 16-bit resolution
Techniques
Scan rate (V/s)
0.000001 to 10000
CV, LSV
Pulse w idth (sec)
0.0001 to 1000
CA, CC
Pulse w idth (sec)
0.001 to 10
DPV, NPV
Sampling interval (sec)
0.0001 to 10
DPV, NPV
Frequency (Hz)
1 to 100000
SWV
Frequency (Hz)
0.1 to 10000
ACV
Frequency (Hz)
0.1 to 5000
SHACV
Frequency (Hz)
0.00001 to 1000000
IMP
Dual-channel measurements are available for CV, LSV, SCV, CA, DPV, NPV, SWV, and i-t.
© 2014 CH Instruments, Inc.
Appendix
257
12.11 Model 800D Series Electrochemical Detector Techniques
Techniques
CV
LSV &
SCV #,&
TAFEL
CA
CC
DPV #,&
NPV #,&
DNPV #,&
SWV &
ACV #,&
SHACV #,&
i-t
DPA
DDPA
TPA
IPAD
BE
SSF
STEP
CP
CPCR
ISTEP
PSA
ECN
OCPT
800D/802D
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810D/812D
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820D/822D
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830D/832D
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840D/842D
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850D/852D
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Galvanostat
RDE control (0-10V out)
Full CV Simulator
Limited CV Simulator
iR Compensation
External Potential Input
Auxiliary Channel
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#
Corresponding polarographic mode can be performed.
&
Corresponding stripping mode can be performed.
Dynamic Range of Selected Experimental Parameters
Parameters
Potential (V)
-10 to +10
Range
Current (A)
0 to ±0.01
Sensitivity (A/V)
10-12 to 0.001
Techniques
Scan rate (V/s)
0.000001 to 500
CV, LSV
Pulse w idth (sec)
0.0001 to 1000
CA, CC
Pulse w idth (sec)
0.001 to 10
DPV, NPV
Sampling interval (sec)
0.00005 to 10
i-t
Frequency (Hz)
1 to 100000
SWV
Single channel (8×0D) or dual channel (8×2D) electrochemical detection. High sensitivity and low noise. Fast 16-bit A/D
converter (1 MHz). Bipotentiostat can also be used for RRDE.
© 2014 CH Instruments, Inc.
258
CH Instruments Model 900D Series
12.12 Model 920D Scanning Electrochemical Microscope
The scanning electrochemical microscope (SECM) was introduced in 19891 as an instrument that could
examine chemistry at high resolution near interfaces. By detecting reactions that occur at a small
electrode (the tip) as it is scanned in close proximity to a surface, the SECM can be employed to obtain
chemical reactivity images of surfaces and to make quantitative measurements of reaction rates.
Numerous studies with the SECM have now been reported from a number of laboratories all over the
world, and the instrument has been used for a wide range of applications, including studies of corrosion,
biological systems (e.g., enzymes, skin, leaves), membranes, and liquid/liquid interfaces. 2 The trapping
and electrochemical detection of single molecules by SECM has also been reported.
1. A. J. Bard, F.-R. F. Fan, J. Kw ak, and O. Lev, Anal. Chem. 61, 132 (1989); U.S. Patent No. 5,202,004 (April 13, 1993).
2. A. J. Bard, F.-R. Fan, M. V. Mirkin, in Electroanalytical Chemistry, A. J . Bard, Ed., Marcel Dekker, New York, 1994, Vol. 18,
pp 243-373.
Model 900D/920D SECM Specifications
Nanopositioner:
X, Y, Z resolution: 1.6 nm w ith Piezo positioner, closed
loop control
8 nm w ith stepper motor positioner
X, Y, Z total distance: 50 mm
Potentiostat / Biptentiostat:
Scanning Probe Techniques:
SECM Imaging (SECM): constant height, constant
current, potentiometric and impedance modes
Probe Approach Curves (PAC)
Probe Scan Curve (PSC): constant height, constant
current, potentiometric, impedance, and constant
impedance modes
Surface Patterned Conditioning (SPC)
Surface Interrogation SECM (SISECM)
Z Probe Constant Current Control
Zero resistance ammeter
2- or 3- or 4-electrode configuration
Floating (isolated from earth) or earth ground
Maximum potential: ±10 V for both channels
Maximum current: ±250 mA continuous (sum of tw o current Sweep Techniques:
channels), ±350 mA peak
Cyclic Voltammetry (CV)
Compliance Voltage: ±13 V
Linear Sw eep Voltammetry (LSV)
Potentiostat rise time: < 1 ms, 0.8 ms typical
Tafel Plot (TAFEL)
Potentiostat bandw idth (-3 dB): 1 MHz
Applied potential ranges (V): ±0.01, ±0.05, ±0.1, ±0.65,
Step and Pulse Techniques:
±3.276, ±6.553, ±10
Staircase Voltammetry (SCV)
Applied potential resolution: 0.0015% of potential range
Chronoamperometry (CA)
Applied potential accuracy: ±1 mV, ±0.01% of scale
Chronocoulometry (CC)
Applied potential noise: <10 mV rms
Differential Pulse Voltammetry (DPV)
Measured current range: ±10 pA to ±0.25 A in 12 ranges
Normal Pulse Voltammetry (NPV)
Measured current resolution: 0.0015% of current range,
Differential Normal Pulse Voltammetry (DNPV)
minimum 0.3 fA
Square Wave Voltammetry (SWV)
Current measurement accuracy: 0.2% if current range >=
1e-6 A/V, 1% otherw ise
AC Techniques:
Input bias current: < 20 pA
AC Voltammetry (ACV)
Second Harmonic AC Voltammetry (SHACV)
Galvanostat:
Fourier Transform AC Voltammetry (FTACV)
Galvanostat applied current range: 3 nA – 250 mA
AC Impedance (IMP)
Applied current accuracy: 20 pA ± 0.2% if > 3e-7 A, ± 1%
Impedance versus Potential (IMPE)
otherw ise
Impedance versus Time (IMPT)
Applied current resolution: 0.03% of applied current range
Measured potential range: ±0.025 V, ±0.1 V, ±0.25 V, ±1 V,
Galvanostatic Techniques:
±2.5 V, ±10 V
Chronopotentiometry (CP)
Measured potential resolution: 0.0015% of measured range
Chronopotentiometry w ith Current Ramp (CPCR)
Multi-Current Steps (ISTEP)
Electrometer:
Potentiometric Stripping Analysis (PSA)
Reference electrode input impedance: 1e12 ohm
© 2014 CH Instruments, Inc.
Appendix
Reference electrode input bandw idth: 10 MHz
Reference electrode input bias current: <= 10 pA @ 25°C
Other Techniques:
Amperometric i-t Curve (i-t)
Differential Pulse Amperometry (DPA)
Double Differential Pulse Amperometry (DDPA)
Triple Pulse Amperometry (TPA)
Integrated Pulse Amperometric Detection (IPAD)
Bulk Electrolysis w ith Coulometry (BE)
Hydrodynamic Modulation Voltammetry (HMV)
Sw eep-Step Functions (SSF)
Multi-Potential Steps (STEP)
Electrochemical Noise Measurement (ECN)
Open Circuit Potential - Time (OCPT)
Various Stripping Voltammetry
Potentiometry
Waveform Generation and Data Acquisition:
Fast w aveform update: 10 MHz @ 16-bit
Fast data acquisition: dual channel 16-bit ADC, 1,000,000
samples/sec simultaneously
External signal recording channel at maximum 1 MHz
sampling rate
2D and 3D Graphics:
•
•
•
•
•
Interactive visualization of SECM surfaces
Color mapping
Laplacian smoothing
Stereoscopic 3D anaglyph imaging
High compatibility (Window s 98, 256 colors and up)
Experimental Parameters:
CV/LSV scan rate: 0.000001 to 10,000 V/s, tw o
channels simultaneously
Potential increment during scan: 0.1 mV @ 1,000 V/s
CA and CC pulse w idth: 0.0001 to 1000 sec
CA minimum sample interval: 1 µs, both channels
CC minimum sample interval: 1 µs
True integrator for CC
DPV and NPV pulse w idth: 0.001 to 10 sec
SWV frequency: 1 Hz to 100 kHz
i-t sample interval: minimum 1 µs, both channel
ACV frequency: 0.1 Hz to 10 kHz
SHACV frequency: 0.1 Hz to 5 kHz
FTACV frequency: 0.1 to 50 Hz, simultaneous acquire
1st, 2nd, 3rd, 4th, 5th, and 6th harmonics ACV data
IMP frequency: 0.00001 Hz to 1 MHz
IMP amplitude: 0.00001 V to 0.7 V RMS
Other Features:
Automatic and manual iR compensation
Current measurement bias: full range w ith 16-bit resolution,
0.003% accuracy
Potential measurement bias: ±10 V w ith 16-bit resolution,
0.003% accuracy
External potential input
Potential and current analog output
Programmable potential filter cutoff: 1.5 MHz, 150 KHz, 15
KHz, 1.5 KHz, 150 Hz, 15 Hz, 1.5 Hz, 0.15 Hz
Programmable signal filter cutoff: 1.5 MHz, 150 KHz, 15
KHz, 1.5 KHz, 150 Hz, 15 Hz, 1.5 Hz, 0.15 Hz
RDE control output: 0-10V (corresponding to 0-10000 rpm),
16-bit, 0.003% accuracy
Digital input/output lines programmable through macro
command
Flash memory for quick softw are update
Serial port or USB port selectable for data communication
Cell control: purge, stir, knock
Maximum data length: 256K-16384K selectable
Real Time Absolute and Relative Distance Display
Real Time Probe and Substrate Current Display
Dual-channel measurements for CV, LSV, CA, DPV, NPV,
SWV, i-t
CV simulation and fitting program, user defined mechanisms
Impedance simulation and fitting program
150
0
80
40
Y / um
i/A
6.00E-10
100
0
X / um
Probe Approach Curve
8.00E-10
50
i/A
SECM Image
0.00E+00
-2.00E-10
-4.00E-10
-6.00E-10
-8.00E-10
4.00E-10
2.00E-10
0.00E+00
-60
-40
-20
Distance / um
© 2014 CH Instruments, Inc.
259
0
260
CH Instruments Model 900D Series
12.13 Model 1000C Series Multi-Potentiostat
The model 1000C series instrument is a computerized eight-channel potentiostat. The system contains
a digital function generator and multiplexed data acquisition circuitry. The multi-potentiostat can work
with eight independent cells or eight working electrodes in the same solution with common reference and
counter electrodes. The potential control range is ±10 V for all channels and the current range is ±10
mA. The instrument is capable of measuring current down to picoamperes. Each electrode can be
individually controlled, including on/off control, potential, and sensitivity settings; each can be set to an
independent potential or the same potential as the primary channel, so that they can sweep or step
potentials together with the primary channel.
The model 1000C series is an upgrade to the model 1000/1000A/1000B series. The instrument allows
eight independent cells, simultaneous or sequential measurements, fast waveform generation and data
acquisition speed (1 MHz @ 16-bit), and easy software update using flash memory.
Many electrochemical techniques are available in this model series, including cyclic voltammetry and
amperometric i-t measurements, with all eight channels available (except for open circuit potential
measurements). The parameters for all channels must be set before running an experiment; you cannot
alter parameter settings during experiments. During a run, you can toggle between single and multi-data
set display (parallel or overlay plots). After a run, you can choose data from any channel for parallel or
overlay plotting.
Techniques for Model 1000C Series
Techniques
CV
LSV &
CA
CC
DPV &
NPV &
SWV &
ACV &
SHACV &
FTACV
i-t
DPA
TPA
SSF
STEP
OCPT
&
1000C
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1010C
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1020C
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1030C
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1040C
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•
Corresponding stripping mode can be performed.
Specifications
8-channel potentiostat
8 independent cells or a multi-WE cell
Potential range (all channels): ±10 V
Applied potential accuracy: ±1 mV, ±0.01% of
scale
Compliance voltage: ±12 V
DPV and NPV pulse width: 0.001 to 10 sec
SWV frequency
1 Hz to 100 kHz (sequential scan)
1 to 3125 Hz (8 channel simultaneous scan)
ACV frequency
1 to 10000 Hz (sequential scan)
© 2014 CH Instruments, Inc.
Appendix
Current range (each channel):10 mA
Reference electrode input impedance: 1012 ohm
Sensitivity scale: 10-9 - 0.001 A/V in 7 ranges
Minimum current resolution: 0.0015% of current
range, min 0.3 pA
Input bias current: < 50 pA
Fast waveform update: 5 MHz @ 16-bit
Fast data acquisition: up to 1 MHz @ 16-bit
CV and LSV scan rate
0.000001 to 5000 V/s (sequential scan)
0.000001 to 25 V/s (8 channel simultaneous
scan)
Potential increment during scan: 0.1 mV @
1,000 V/s
CA and CC pulse width: 0.0001 to 1000 sec
CA and CC sample interval:
1e-6 to 50 s (sequential step)
8e-5 to 50 s (8 channel simultaneous step)
© 2014 CH Instruments, Inc.
261
1 to 312 Hz (8 channel simultaneous scan)
SHACV frequency
1 to 5000 Hz (sequential scan)
1 to 250 Hz (8 channel simultaneous scan)
FTACV frequency: simultaneously acquire 1st,
2nd, 3rd, 4th, 5th, and 6th harmonics data
0.1 to 50 Hz (sequential scan)
0.1 to 34 Hz (8 channel simultaneous scan)
Current low-pass filters
Current analog output
Cell control: purge, stir, knock
Data length: 128K - 4096K each channel
Dimensions: 14.2"(W) × 9.2"(D) × 4.7"(H)
262
CH Instruments Model 900D Series
12.14 Model 1100C Series Power Potentiostat / Galvanostat
The Model 1100C series pow er potentiostat/galvanostat is designed for electrochemical applications that require relatively
large current and high compliance voltage, such as battery studies, corrosion, electrolysis, and electroplating. The potential
control range is ±10 V, the current range is ±2 A, and the compliance voltage is ±25 V. The instrument contains a high speed
digital function generator, a fast data acquisition system, current signal filters, iR compensation circuitry, a potentiostat, and a
galvanostat (1140C only). The function generator can update at a 10 MHz rate, and the maximum sampling rate is 1 MHz at
16-bit resolution. This series is capable of measuring current dow n to tens of picoamperes. The 1100C series is capable of
measuring current dow n to tens of picoamperes. The steady state current of a 10 &mu;m disk electrode can be readily
measured w ithout external adapters. The instrument provides a very w ide dynamic range of experimental time scales. For
instance, the scan rate in cyclic voltammetry can be up to 1000 V/s w ith a 0.1 mV potential increment, or 5000 V/s w ith a 1
mV potential increment. The potentiostat/galvanostat uses a 4-electrode configuration, allow ing it to be used for liquid/liquid
interface measurements and eliminating the effect of the contact resistance of connectors and relays for high current
measurements. The data acquisition systems allow an external input signal (such as spectroscopic) to be recorded
simultaneously w ith electrochemical data.
Similar features can also be obtained using the combination of the model 600E series and the CHI680C Amp Booster.
How ever, the model 1100C series is more compact and less expensive.
Specifications
Potentiostat
Galvanostat (Model 1140C)
Potential range: -10 to 10 V
Applied potential resolution: 0.0015 % of potential range
Applied potential accuracy: ±2 mV, ±0.02% of scale
Potentiostat rise time: < 2 µs
Compliance voltage: ±25 V
3- or 4-electrode configuration
Current range: ±2 A
Reference electrode input impedance: 10-12 ohm
Sensitivity scale: 10-12 - 0.1 A/V in 12 ranges
Input bias current: < 50 pA
Current measurement resolution: < 1 pA
Potential update rate: 10 MHz
Data acquisition: 16-bit @ 1 MHz
External voltage signal recording channel
External potential input
Automatic and manual iR compensation
Potential and current analog output
RDE control voltage output: 0-10 V (selected models)
CV and LSV scan rate: 0.000001 to 5000 V/s
Potential increment during scan: 0.1 mV @ 1000 V/s
CA and CC pulse w idth: 0.0001 to 1000 sec
CA and CC Steps: 320
DPV and NPV pulse w idth: 0.001 to 10 sec
SWV frequency: 1 Hz to 100 kHz
CA and i-t sample interval: minimum 1 µs
ACV frequency: 0.1 Hz to 10 kHz
SHACV frequency: 0.1 Hz to 5 kHz
IMP frequency: 0.00001 Hz to 10 kHz
Automatic potential and current zeroing
Potential and signal low -pass filters (8-decade freq.
range, auto/manual)
Potential and current analog output
Cell control: purge, stir, knock
Flash memory for quick softw are update
USB or serial port selectable for data communication
Data length: 128K - 4096K selectable
Chassis dimensions: 14.2"(W) × 9.2"(D) × 4.7"(H)
Techniques for Model 1100C Series
Technique
Cyclic Voltammetry (CV)
Linear Sw eep Voltammetry (LSV) &
Staircase Voltammetry (SCV) #,&
Tafel Plot (TAFEL)
Chronoamperometry (CA)
Chronocoulometry (CC)
Differential Pulse Voltammetry (DPV) #,&
Normal Pulse Voltammetry (NPV) #,&
Differential Normal Pulse Voltammetry (DNPV) #,&
Square Wave Voltammetry (SWV) &
AC Voltammetry (ACV) #,&,$
2nd Harmonic AC Voltammetry (SHACV) #,&,$
Amperometric i-t Curve (i-t)
1100C
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1110C
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1120C
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1130C
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1140C
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1150C
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© 2014 CH Instruments, Inc.
Appendix
Differential Pulse Amperometry (DPA)
Double Differential Pulse Amperometry (DDPA)
Triple Pulse Amperometry (TPA)
Bulk Electrolysis w ith Coulometry (BE)
Sw eep-Step Functions (SSF)
Multi-Potential Steps (STEP)
AC Impedance (IMP)
Impedance - Time (IMPT)
Impedance - Potential (IMPE)
Chronopotentiometry (CP)
Chronopotentiometry w ith Current Ramp (CPCR)
Potentiometric Stripping Analysis (PSA)
Open Circuit Potential - Time (OCPT)
Galvanostat
Full version of CV simulator
Limited version of CV simulator
Impedance simulation and fitting program
#
Corresponding polarographic mode can be performed.
& Corresponding stripping mode can be performed.
$ Phase-selective data are available.
© 2014 CH Instruments, Inc.
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263
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264
CH Instruments Model 900D Series
12.15 Model 1200B Series Handheld Potentiostat / Bipotentiostat
The model 1200B series instrument is a computerized hand-held potentiostat/bipotentiostat. The system contains a digital
function generator, a data acquisition system, and a potentiostat/bipotentiostat, and it is w ell suited for electroanalysis and
sensor studies. The potential range is ±2.4 V and the current range is ±2 mA. This series is capable of measuring current
dow n to 100 pA. The steady state current of a 10 µm disk electrode can be readily measured. The size of the instrument is
7" (W) × 4.5" (D) × 1" (H), and it is pow ered through a USB port, w ithout any need for an AC adapter or batteries. The
instrument can be used for electroanalysis and sensor studies. Due to its small size, light w eight, and low cost, it is
particularly useful for field applications and teaching laboratories.
The Model 1200B series allow s ±7.5 V compliance voltage, w hich ensures its w orking potential range of ±2.4 V for most
electrochemical systems. It also uses dual 16-bit DAC and 16-bit ADC for high resolution and accuracy.
The model 1200B series potentiostats (12×0B, 1205B, and 1207B) and bipotentiostats (12×2B, 1206B, and 1208B) are
offered in several models tailored to meet a w ide range of applications and budget levels.
Specifications
Potentiostat / bipotentiostat
Potential range: -2.4 to 2.4 V
Compliance voltage: ±7.5 V
Current range: ±2 mA
CV and LSV scan rate: 0.000001 to 10 V/s
CA and CC pulse w idth: 0.001 to 1000 sec
CA and CC Steps: 1 - 320
DPV and NPV pulse w idth: 0.001 to 10 sec
SWV frequency: 1 to 5000 Hz
ACV frequency: 0.1 to 2000 Hz
Low -pass filter for current measurements
Data length: 128K - 4096K selectable
Chassis dimensions: 7"(W) × 4.5"(D) × 1"(H)
-12
Reference electrode input impedance: 10
ohm
-9
Sensitivity scale: 10 - 0.001 A/V in 7 ranges
Input bias current: < 100 pA
Current measurement resolution: < 1 pA
Data acquisition: 16 bit @ 1 MHz
Techniques for Model 1200B Series
Techniques
Cyclic Voltammetry (CV)*
Linear Sw eep Voltammetry (LSV)
Chronoamperometry (CA) *
&
*
Chronocoulometry (CC)
1200B/
1202B
•
•
1205B/
1206B
•
•
1207B/
1208B
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1220B/
1222B
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1230B/
1232B
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1240B/
1242B
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&
Differential Pulse Voltammetry (DPV) *
&
Normal Pulse Voltammetry (NPV) *
&
Differential NPV (DNPV) *
&
Square Wave Voltammetry (SWV) *
&
AC Voltammetry (ACV)
&
2nd Harmonic AC Voltammetry (SHACV)
Amperometric i-t Curve (i-t) *
1210B/
1212B
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Differential Pulse Amperometry (DPA)
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Double DPA (DDPA)
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Triple Pulse Amperometry (TPA)
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Sw eep-Step Functions (SSF)
•
Multi-Potential Steps (STEP)
Open Circuit Potential - Time (OCPT)
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Full version of CV simulation / fitting
Limited version of CV simulation / fitting
•
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&
Corresponding stripping mode can be performed.
* Second channel (bipotentiostat mode) can be performed.
Note:
12×0B, 1205B, and 1207B are single potentiostat models; 12×2B, 1206B, and 1208B are bipotentiostat models.
© 2014 CH Instruments, Inc.
Appendix
265
12.16 Model 1550A Pico-Liter Solution Dispenser
The CHI1550A solution dispenser is designed for making high density and high accuracy solution arrays,
which can be used in a wide variety of chemical, biological, and medical applications. The solution
dispenser consists of a high-resolution three-dimensional positioner, a piezoelectric jetting device, and a
sample platform, as shown in the Figure below.
Figure. Diagram of the solution dispenser
The three-dimensional positioner can travel a distance of 50 mm in all three directions with 0.1
micrometer resolution, allowing high-precision patterning. This is particularly important when multiple
overlapping solution components need to be dispensed.
The jetting device can dispense single drops of solutions with viscosity less than 40 centipoise and
surface tension in the range of 0.02-0.07 N/m. Solutions with properties outside these limits can be
jetted if changes to the properties can be achieved with solvents or changes in temperature. With a
default nozzle size of 60 microns, the jetting device can produce drops ranging from 100-200 picoliters in
volume, depending on the operating parameters and solution composition.
The CHI1550A solution dispenser control software is very user-friendly for creating binary, ternary, and
quaternary arrays of spots containing mixtures of solutions. Instead of using a manually created look-up
table for solution dispensing patterns, pattern creation is facilitated by our software, which can also
provide commonly used patterns as a default for binary, ternary, and quaternary arrays. The positioner
can memorize certain critical positions, such as the solution loading point and first dispensing point,
allowing the jetting device to go to these positions easily and quickly.
The array pattern can be examined graphically, and it will also be displayed during the dispensing
process.
© 2014 CH Instruments, Inc.
266
CH Instruments Model 900D Series
Figure. Micropositioner and sam ple stand
System requirements
Operating System: Windows 95 / 98 / NT / Me / 2000 / XP / Vista / 7 / 8
Communication between PC and instrument: USB or RS-232 serial port
Hardware Specifications
Micropositioner:
Jetting Device:
Three high-resolution stepper motors
Maximum range of motion: 50 mm
Motor resolution: 8 nm
Stall Load: 50 N
Maximum Speed: 4 mm / sec
Nozzle: 60 microns
Droplet size: 100-200 picoliters
Control voltage: 0 - 150 V
Protective holder
Three translation stages
Maximum range of motion: 25 mm
Angular deviation: < 200 microrad
Load capacity: 156 N
Load capacity (vertical): 67 N
© 2014 CH Instruments, Inc.
Appendix
267
12.17 Picoamp Booster/Faraday Cage and Multiplexer
CHI200(B) Picoamp Booster and Faraday Cage
With the CHI200(B) Picoamp Booster and Faraday Cage, current down to a few picoamperes can be
readily measured. The CHI200 is compatible with the model 600/A, 700/A series of instruments, while
the CHI200B is compatible with the model 600B/C/D/E and 700B/C/D/E series. When used with the
700/A/B/C/D/E series bipotentiostat, the Picoamp Booster will affect only the primary channel.
The internal sensitivity of the 600E series is the same as the Picoamp Booster (10-12 A/V). However, the
bias current of the 600E series input can be as high as 50 pA. The Picoamp Booster has a lower bias
current, and it also brings the preamplifier close to the electrode, resulting in lower noise. The Faraday
cage also makes it possible to make relatively fast measurements of small currents.
When the Picoamp Booster is connected and the sensitivity scale is at or below 1e-8 A/V, the Picoamp
Booster will be automatically enabled. Otherwise it will be disabled. Detection and enabling/disabling of
the Picoamp Booster are fully automatic and do not require user intervention.
The Picoamp Booster will be disabled for techniques using automatic sensitivity switching, such as Tafel
plots (TAFEL) and bulk electrolysis (BE), and galvanostatic techniques. For galvanostatic techniques,
such as chronopotentiometry (CP), chronopotentiometry with Current Ramp (CPCR), Multi-Current Steps
(ISTEP), and Potentiometric stripping analysis (PSA), the Picoamp Booster will not work. However, it
works with AC impedance (IMP).
In addition to allowing weak signal measurements, the Faraday cage is useful for eliminating electrical
interference, especially line frequency noise. If the electrochemical cell is picking up electrical noise
from the environment, the additional use of the Faraday cage is strongly recommended.
Before connecting the Picoamp Booster, turn the instrument power off. Connect the Picoamp Booster to
the 6-pin "Electrodes" connector on the rear panel of the instrument. Also connect the DB-25 connector
of the Picoamp Booster to the "Cell Control" connector on the rear panel of the instrument with the
straight through DB-25 cable (included), then turn the instrument power on.
The DB-25 connector provides power and control lines (see Cables and Connections in the Appendix).
When the DB-25 connector is disconnected, you can still do experiments with the Faraday cage,
although the Picoamp Booster will be disabled.
To purge inert gas, unscrew one of the screws on the back of the faraday cage to open a hole for inert
gas tubing.
When the Picoamp Booster is not in use, please disconnect the DB-25 cable.
CHI684 Multiplexer
The CHI684 is a multi-channel multiplexer for the model 400/A/B, 600A/B/C/D/E, 700A/B/C/D/E, 800B/
C, 900B/C/D, and 1100A/B/C series. The multiplexer switches four lines (working, sensing, reference,
and counter for single-channel potentiostats; working, 2nd working, reference, and counter for
bipotentiostats). You can have up to 64 cells, but only one cell can be connected at a time.
The multiplexer is controlled using the Multiplexer command under the Control menu. You can select
any channel(s) and run experiments in a sequence of selected channels. Data will automatically be
saved to file after each run. You can also be prompted before each channel run.
Arbitrary channels can be set immediately. An experiment can then be run for that particular channel.
© 2014 CH Instruments, Inc.
268
CH Instruments Model 900D Series
Two Macro commands are available for the multiplexer. One is "mch:##", which allows the user to
choose an individual channel. The other macro command is "mchn". This is used in a For...Next loop to
select the channel according to the For...Next loop counter.
The minimum number of channels for the CHI684 is 8. The channel increment is 8. The maximum
number of channels is 64.
© 2014 CH Instruments, Inc.
Appendix
269
12.18 Amp Booster and Liquid/Liquid Interface Adapter
CHI680C Amp Booster
With the CHI680C Amp Booster, current can be measured up to 2 A. The CHI680 is compatible with our
Model 600/A/B/C/D series instruments. The CHI680C is compatible with our Model 600D/E series of
instruments. You can stack the CHI600D/E and the CHI680C together. The CHI680C can also be
connected to the model 700E series, but it will only work for the primary channel.
When the Amp Booster is connected, cell control signals such as purge, knock, and stir will be
disabled.
The Amp Booster will also allow low current measurements. You may need to use a Faraday cage to
eliminate line frequency noise when the scan rate is above 50 mV/s.
The frequency response of the Amp Booster is somewhat lower than that of the 600/A/B/C/D/E. For high
speed experiments, the Amp Booster should be disconnected.
Before connecting the Amp Booster, turn the instrument power off. Connect the 6-pin connector of the
Amp Booster to the "Electrodes" connector on the rear panel of the CHI6××D. Also connect the "Cell
Control" ports of the Amp Booster and the instrument with a straight through DB-25 cable (included).
You can then turn the power on for both the instrument and the Amp Booster. It is generally good
practice to turn the instrument on before the Amp Booster, and to turn the Amp Booster off before the
instrument.
The cell connector is a 6-pin connector with four cell leads. The green, white, and red clips correspond to
the working, reference, and counter electrodes, respectively. The black clip is for the sensing electrode
of the 4-electrode configuration, which can be turned on or off with the "4 Electrodes" box using the Cell
command under the Control menu. When the 4-electrode option is on, you should connect the sensing
lead to the working electrode (short the green and black leads together). The 4-electrode configuration is
useful for liquid/liquid interface or high current measurements. It helps eliminate the resistance (about
0.2-0.3 ohms) due to the connectors, relays, and printed circuit board traces.
If you think there might be something wrong with the hardware, please conduct a hardware test with the
Amp Booster disconnected. If the instrument passes the test, then connect the Amp Booster and test it
with a standard resistor. For instance, conduct a CV experiment and verify that a straight line with a
slope of voltage / resistance is correctly obtained.
CHI682 Liquid/Liquid Interface Adapter
Liquid/liquid interface studies are very important in applications involving charge transfer, chemical
sensing, drug release, and solvent extraction, among others. This typically involves two reference
electrodes and two auxiliary electrodes. The modified potentiostat controls the potential difference
between two reference electrodes in two phases, while measuring the current passing through two
auxiliary electrodes. The CHI682 Liquid/Liquid Interface Adapter is compatible with our model 700A
series. It is fully automatic and user-friendly. Most electrochemical techniques can be used, albeit
without galvanostat or bipotentiostat functions.
This is a legacy accessory for the model 700A series. Liquid/liquid interface measurement capabilities
using 4-electrode configuration are built into our model 400/A/B, 600A/B/C/D, 700B/C/D, 800B/C, 900B/
C, and 1100/A/B series instruments, with no need for the CHI682 Liquid/Liquid Interface Adapter.
© 2014 CH Instruments, Inc.
270
CH Instruments Model 900D Series
12.19 Accessories
Part No.
CHI101
CHI101P
CHI102
CHI102P
CHI103
CHI104
CHI104P
CHI105
CHI105P
CHI106
CHI106P
CHI107
CHI107P
CHI108
CHI108P
CHI111
CHI111P
CHI112
CHI112P
CHI115
CHI116
CHI116P
Description
2 mm dia. Gold Working Electrode
2 mm dia. Gold Working Electrode
2 mm dia. Platinum Working Electrode
2 mm dia. Platinum Working Electrode
2 mm dia. Silver Working Electrode
3 mm dia. Glassy Carbon Working
Electrode
3 mm dia. Glassy Carbon Working
Electrode
12.5 µm dia. Gold Microelectrode
12.5 µm dia. Gold Microelectrode
25 µm dia. Gold Microelectrode
25 µm dia. Gold Microelectrode
10 µm dia. Platinum Microelectrode
10 µm dia. Platinum Microelectrode
25 µm dia. Platinum Microelectrode
25 µm dia. Platinum Microelectrode
Ag/AgCl Reference Electrode
Ag/AgCl Reference Electrode
Non-Aqueous Ag/Ag+ Reference
Electrode 1
Non-Aqueous Ag/Ag+ Reference
Electrode 1
Platinum Wire Counter Electrode
10 mmm dia. Platinum SECM Tip
10 mmm dia. Platinum SECM Tip
Unit
1
3/pk
1
3/pk
1
1
3/pk
Part No.
CHI117
CHI117P
CHI120
CHI125A
CHI127
CHI128
CHI129
1
3/pk
1
3/pk
1
3/pk
1
3/pk
1
3/pk
1
CHI130
CHI131
CHI132
CHI133
CHI134
CHI135
CHI140A
CHI150
CHI151
3/pk
CHI172Model #
CHI200
CHI201
CHI202
CHI220
CHI221
1
1
3/pk
CHI152
CHI222
CHI223
Description
Unit
25 µm dia. Platinum SECM Tip
1
25 µm dia. Platinum SECM Tip
3/pk
Electrode Polishing Kit 2
1
Polished, Bounded, Mounded 100A Ti + 1
1000 A Gold Crystal for EQCM
EQCM Cell
1
Reference Electrode for EQCM Cell
1
Pt Wire Counter Electrode for EQCM
1
Cell
Thin-Layer Flow Cell
1
GC Working Electrode for Flow Cell
1
Au Working Electrode for Flow Cell
1
Pt Working Electrode for Flow Cell
1
Reference Electrode for Flow Cell
1
25 µm Spacer for Flow Cell
4/pk
Spectroelectrochemical Cell
1
Calomel Reference Electrode
1
Mercury/Mercurous Sulfate Reference
1
Electrode
Alkaline/Mercurous Oxide Reference
1
Electrode
Electrode leads for a particular
1
instrument model number
Picoamp Booster and Faraday Cage 3
1
Picoamp Booster
1
Faraday Cage
1
Simple Cell Stand 4
1
Cell Top (including Pt w ire counter
1
electrode, not a replacement part for
the CHI200 cell stand) 5
Glass Cell
1
Teflon Cap 5
1
Notes:
1. Ag+ solution (typically 10 mM) should be prepared w ith the supporting electrolyte and AgNO3 (not included) and filled into
the reference electrode compartment using a syringe (not included). Detailed instructions are included w ith the
components.
2. The electrode polishing kit contains 1 bottle of 1.0 micron Alpha alumina pow der, 1 bottle of 0.3 micron Alpha alumina
pow der, 3 bottles of 0.05 micron Gamma alumina pow der, 2 glass plates for polishing pads, 5 pieces of 73 mm diameter
1200 grit CarbiMet disks (grey-colored), 5 pieces of 73 mm diameter Mastertex polishing pads (w hite-colored), and 10
pieces of 73 mm diameter Microcloth polishing pads (brow n-colored).
3. The Picoamp Booster and Faraday Cage allow current measurements dow n to 1 pA. Usage is fully automatic and
compatible w ith our model 600E and 700E series instruments (primary channel only).
4. Made of stainless steel and Teflon. Not remote controllable. Four glass cells are included.
5. Not a replacement part for the CHI220 Cell Stand.
© 2014 CH Instruments, Inc.
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