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Run the Multiplexed Potentiostatic EIS Repeating standard technique by selecting Experiment > Electrochemical Impedance > Multiplexed Potentiostatic EIS Repeating from the Framework™ menu bar. This initiates the following sequence of events:
1.Framework™ creates a Runner window, and the Multiplexed Potentiostatic EIS Repeating.exp script is run in this window.
2.The script creates the Setup dialog box which becomes the active window and accepts changes in the experimental parameters. This Setup window remembers the experimental settings from the last time this script was run. To restore the parameters to the values defined in the script, click the Default button.
3.The script now obtains the use of the potentiostat specified during Setup and opens the data file using the Output name. If the potentiostat is in use or the file cannot be opened, the script returns you to the Setup dialog box. The file header information is written to the data file. This information is written to the file prior to data acquisition. If the experiment is aborted, the file contains only this information. This header information includes:
•Tags identifying possible analyses.
•The current time and date.
•A list of the Setup parameters.
4.The script loops through the active Channels you selected in Setup, starting from the lowest active channel. It runs an entire EIS test on each selected Channel, beginning with Conditioning and Eoc Delay. The EIS spectrum is recorded from the Initial Freq. to the Final Freq. When the first test is finished after reaching set Total # spectra parameter, the script runs the test on the next active Channel. The script runs one test on each active Channel:
a.The script conditions the electrode if Conditioning was specified in the Setup. Conditioning is done by applying a fixed potential for a defined time. It establishes a known surface state on the working electrode. A plot of current versus time is displayed during the Conditioning.
b.The cell is turned off and the specimen's Eoc is measured. If an Initial Delay is turned on in the Setup, this step lasts for the time specified as the Delay Time, or until the potential stabilizes. If no Initial Delay is specified, this step only lasts long enough for Eoc to be measured. A plot of potential versus time is always displayed. The last measured potential is recorded as Eoc for the first acquired EIS spectrum.
c.The script then sets up data acquisition. The cell is turned on and the DC Voltage requested in setup is applied to the cell. The Initial Frequency is then output and the cell's response to this frequency is measured using the selected FRA. If the readings of both the E and I signals are acceptable, the script proceeds to the frequency sweep. If the values are not acceptable, the script generates new estimate for the cell's impedance, resets the measurement parameters for this impedance, and reruns the measurement. If an acceptable reading cannot be reached after a set number of attempts, the script reports an error, asks if you to quit or continue, and waits for your answer.
d.In the frequency sweep, the script first calculates the desired frequency. For the Nth step in the loop, the frequency is calculated as follows:
if Initial Frequency > Final Frequency, Log Increment = – Log Increment.
This calculated frequency is then adjusted slightly because of the finite resolution of the oscillator and to avoid harmonics of the power-line frequency. The script then sets the measurement parameters to measure an impedance equal to the last recorded impedance and then takes an FRA reading. If the readings of both the E and I signals are acceptable, the script converts the readings to an impedance, records the impedance point on disk, updates the displayed curve, and then proceeds to the next frequency in the frequency sweep. If an acceptable reading cannot be reached after a set number of attempts, the script reports an error, asks if you to quit or continue, and waits for your answer.
e.When the calculated frequency exceeds the Final Frequency after the first measured spectrum and if a Secondary Delay is turned on in the Setup, this step lasts for the time specified as the Delay Time, or until the potential stabilizes. If no Secondary Delay is specified, this step only lasts long enough for Eoc to be measured. A plot of potential versus time is always displayed. The last measured potential is recorded as Eoc for all consecutively acquired EIS spectrum. The next EIS spectra are recorded according to steps 4c to 4e.
f.After reaching the set Total # spectra parameter, the script switches to the next active Channel selected and repeats the whole EIS test (steps 4a to 4f).
5.When the measurement of the last active Channel is done, the script halts and waits for you to click F2-Skip. When you do so, the script closes everything that's open, including the Runner window.