Cyclic Voltammetry Experimental Sequence
- Framework™ creates a runner window, and the Cyclic Voltammetry.exp script is run in this window.
- The script creates the Setup dialog box, which becomes the active window and accepts changes in the experimental parameters. This Setup box 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. If the Advanced Pstat Setup is on, a second Setup dialog box with hardware configuration details becomes the active window, allowing you to modify the hardware configuration used during the experiment.
- The script next obtains the use of the potentiostat specified during Setup and opens the data file using the Output File 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 prior to data-acquisition. If the experiment is aborted, the output file contains only this information. This header information includes: Tags identifying possible analyses, The current time and date, A list of the Setup parameters and hardware configuration
- If Init. Delay is on, then the cell is turned off and the specimen's Eoc is measured for the time specified as the Init. Delay time, or until the potential stabilizes to a value less than the stability setting. A plot of potential versus time is always displayed. The last measured potential is recorded as Eoc. If Init. Delay is off, this step is skipped and Eoc is assumed to be 0.0 V vs. Ref.
- The script conditions the electrode if Conditioning was specified in the Setup. Conditioning is done by applying a fixed potential for a defined time. A plot of current versus time is displayed during the Conditioning.
- Finally an actual scan occurs. The potential of the sample is set to Initial E and held at that value for the Equil. Time. The potential is then swept from the Initial E to Scan Limit 1, then to Scan limit 2 and then toFinal E. If Scan limit 2 equals Final E, then the scan stops at that value. Current readings at fixed voltage-intervals are taken during the sweep. The voltage interval between steps is defined as the Resolution in the Setup dialog box. If the number of Cycles exceeds one, the potential repeats the sweep for n cycles.The sweep is actually a staircase ramp. The sample is potentiostatted at the Initial E, a delay of one Sample Period occurs (Sample Period = 1/Scan Rate × Resolution), and a reading of the current is taken. The potential is then stepped by a few mV as defined by Resolution, a delay of one Sample Period occurs, and the next current reading is taken. Stepping the potential, delaying and acquiring data points continues until the potential equals the Final E.
- If Autoranging was selected in Setup, at each point the current range is automatically switched to the optimal range for the measured cell current. If Positive Feedback IR Compensation has been selected all data are continuously corrected for IR-drop. If Current Interrupt IR Compensation has been selected, each potential is corrected for the measured IR-drop of the preceding point. Plots of I vs. E are displayed during the steps.
- The data are written to the output file and the script cleans up and halts. When the scan is over, the cell is turned off. The acquired data are written to the output file. The script then waits for you to click the Skip button. When you do so, the script closes everything that's open, including the runner window.