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<< Click to Display Table of Contents >> Navigation: Experiments > G - Electrochemical Impedance > Techniques > OptiEIS Potentiostatic > OptiEIS Potentiostatic - Experimental Sequence |
Run the OptiEIS Potentiostatic standard technique by selecting Experiment > Electrochemical Impedance > OptiEIS Potentiostatic from the Framework™ menu bar. This initiates the following sequence of events:
1.Framework™ creates a Runner window, and the OptiEIS Potentiostatic.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 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.
5.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.
6.The script then sets up data acquisition via the following steps:
a.The multi-sine signal is calculated based on the frequency range and amplitude specified during Setup. The phase is optimized so that large constructive interference is avoided.
b.The cell is turned on and the signal is applied for two cycles in order to set up the potentiostat’s ranges and offsets for the best signal-to-noise ratio.
c.The signal is applied for another three cycles to check that the amplitudes of individual sine waves are well-adjusted (power-leveling).
d.The power-leveled signal is phase-optimized a final time.
e.The potentiostat is optimized following another two cycles with the new optimized signal.
f.The signal is applied to the cell until a stable, low-noise response is observed, or for a maximum of 20 cycles.
7.Pressing the F2-Skip button during any step quits the OptiEIS experiment with no data saved, because the Fourier transform of partial data cycles leads to incorrect answers.