Potentiostatic CombiEIS Experimental Sequence
Run the Potentiostatic CombiEIS script by selecting Experiment>Electrochemical Impedance>CombiEIS Potentiostatic. This initiates the following sequence of events:
- The Framework™ creates a Runner window that will be used to display the experiment while running.
- The script creates the Setup dialog box and accepts changes in the parameters.
- The script now obtains use of the potentiostat that was selected during the Setup, and opens the data file specified during the Setup.
- All input parameters are checked to see if they are valid. If there is a problem, the script returns to the Setup dialog box.
- The file header information is written to the data file. This header information includes: (a) Tags identifying possible analyses; (b) The current time and date; (c) A list of the Setup parameters. This information is written to the file prior to data-acquisition. If the experiment is aborted prior to acquisition of the first data point, the output file contains only this information.
- 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.
- 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.
- The script then sets up data-acquisition via the following steps:
The script determines if it is better to run a combination of the two techniques based on the frequency range, or whether the single-sine or the OptiEIS alone is the best choice. The minimum frequency must be below 0.01 Hz for OptiEIS to be included. The maximum frequency must be greater than Min Freq. × 4096 for single-sine to be included.
The script determines the split point as Min Freq. × 4096.
The OptiEIS signal is calculated and optimized as in the standard OptiEIS technique.
The single-sine portion of the scan is started, and individual sinusoidal responses are measured from the Max Freq. down to the split point, as calculated previously.
The OptiEIS portion is completed and the data is added to the plot.
- Pressing the F2-SKIP button during the single-sine portion prompts you to continue the experiment or terminate the test. Any data acquired up to that point are saved.
Pressing the F2-SKIP button during the OptiEIS portion quits the experiment, and only the data from the single-sine portion are saved. Partial data cycles from OptiEIS are discarded because the Fourier transform leads to incorrect answers.