Potentiostatic Mode Electrochemical Noise - Setup Parameters

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Potentiostatic Mode Electrochemical Noise - Setup Parameters

Description

 

4 - Potentiostatic Mode ECN

 

Parameter

Description

Units

Pstat

Select the potentiostat/galvanostat to perform the experiment. Each radio button corresponds to an installed potentiostat. You can select only one potentiostat at a time. Potentiostats that are already in use are marked with an asterisk. They can be selected but cannot be used.

 

Test Identifier

A string that is used as a name. It is written to the data file, so it can be used to identify the data in database or data manipulation programs. The Identifier string defaults to a name derived from the technique's name. While this makes an acceptable curve label, it does not generate a unique descriptive label for a data set. The Identifier string is limited to 80 characters. It can include almost any normally printable character. Numbers, upper- and lower-case letters, and the most common punctuation characters including spaces are valid.

 

Notes...

Enter several lines of text that describe the experiment. A typical use of Notes is to record the experimental conditions for a data set.

 

Notes defaults to an empty string and is limited to 400 characters. It can include all printable characters including numbers, upper- and lower-case letters, and the most common punctuation including spaces. Tab characters are not allowed in the Notes string. Press the Notes button on the right-hand side to open a separate Notes dialog box.

 

Output File

The name of the file in which the output data are written. By default, it is saved in the default file directory.

 

The input can be a simple file name with no path information. In this case the output file is located in the default file directory. The default file directory is specified in the Gamry.INI file under the [Framework] section with a Key named DataDir. The default path can be changed using the Path command in the Options menu. It can also include path information, such as C:\MY GAMRY DATA\YOURDATA.DTA. In this example, the data are written to the YOURDATA.DTA file in the MY GAMRY DATA directory on drive C. The default value of the Output File parameter is an abbreviation of the technique name with a *.DTA filename extension. We recommend that you use a *.DTA file name extension for your data file names. The data analysis package assumes that all data files have *.DTA extensions.

 

If the script is unable to open the file, an error message box, Unable to Open File, is generated. Common causes for this type of problem include:

•Invalid file name.

•The file is already open under a different Windows® application.

•The disk is full.

 

After you click the OK button in the error box, the script returns to the Setup where you can re-enter the file name.

 

Applied Voltage

The voltage applied to the working electrode during the measurement. Enter the voltage either versus the reference electrode potential (vs. Eref) or open-circuit potential (vs. Eoc). The allowed range is ±8 V with a resolution of 0.125 mV.

volts (V)

Sample Area

The surface area of the sample that is exposed to the solution. The software uses the sample area to calculate the current density and corrosion rate (if applicable). If you do not want to enter an area, we recommend that you leave it at the default value of 1.00 cm².

 

Gamry tip bulb

Do not enter a value of zero!

cm2

Block Time

The length of time in which data are acquired for each block. Each block of data is later reduced to a single data point. The allowed range for the Block Time parameter is controlled by the Sample Period parameter which is discussed in the Sample Period section.

seconds (s)

Sample Period

The time between data points within a data block. The minimum value that we recommend with the unmodified scripts is 0.1 s. The longest Sample Period allowed is 600 s.

 

Sample periods down to 0.005 seconds usually do not cause errors, but do not yield any additional information. Analog filters in the potentiostat remove the higher-frequency information that faster data rates would measure. The Number of Points in each data block is obtained from the formula:

 

 

Each block must contain between 3 and 4000 data points. Data blocks containing fewer than 10 points are not recommended, because statistical tests on small samples are subject to large errors.

seconds (s)

Init. Delay

Use the Initial Delay parameter to tell the system your definition of a stable potential and when to begin the actual measurement. If the absolute value of the Eoc drift-rate falls below the Stability parameter, the Initial Delay phase ends immediately and the experiment begins, disregarding the Time parameter. The drift rate can never fall below zero, so entering a Stability value of zero ensures that the Initial Delay will not end prematurely. A typical value is 0.05 mV/s. The lower limit of the Stability parameter is set by your patience. For example, a stability of 0.01 mV/s indicates a drift of less than 1 mV within 100 seconds.

seconds (s), mV/s

Repeat Time

The time between each test on the cell.

minutes (min)

Total Time

The duration of the experimental run. The script keeps track of the elapsed time from the start of the experiment. At the start of each test, the elapsed time is compared to the Total Time. If the elapsed time is greater than or equal to the Total Time, the experiment is halted and the Runner window is closed.

 

Gamry tip bulb

A Total Time of zero results in no tests being run.

hours (hr)