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<< Click to Display Table of Contents >> Navigation: Experiments > K - Solar Cells > Intensity Modulated Photovoltage Spectroscopy > IMVS - Experimental Sequence |
Run the Intensity Modulated Photovoltage Spectroscopy standard technique by selecting Experiment > Electrochemical Energy > Intensity Modulated Photovoltage Spectroscopy from the Framework™ menu bar. This initiates the following sequence of events:
1.Framework™ creates a Runner window, and the IMVS.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 then sets up data acquisition. The MASTER potentiostat is switched to galvanostatic mode and the LED is turned on. The SERF potentiostat is set to galvanostatic mode. The cell is open (open-circuit condition). The requested DC Current superimposed by the selected AC Current is generated at the Initial Frequency and the cell’s response to this frequency is measured. If the readings are acceptable, the script proceeds to the frequency sweep. If the values are not acceptable, the script adjusts voltage and current ranges, resets the measurement parameters, 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.
5.In the frequency sweep, the script first calculates the desired frequency. For the Nth step in the loop, the frequency is calculated as follows: Log Increment = 1.0 / Points/decade; if Initial Frequency > Final Frequency, Log Increment = –Log Increment; Frequency = 10[log(Initial Frequency) + N × 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 a potential equal to the last recorded potential and then takes an FRA reading. If the readings are acceptable, the script converts the readings to a magnitude parameter, records this 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 want to continue, and waits for your answer.
6.When the calculated frequency exceeds the Final Frequency, the script halts and waits for you to click the F2-Skip button. When you do so, the script closes everything that's open, including the Runner window.