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<< Click to Display Table of Contents >> Navigation: Experiments > F - Pulse Voltammetry > Techniques > Normal Pulse Voltammetry > Normal Pulse Voltammetry - Experimental Sequence |
Run the Normal Pulse Voltammetry standard technique by selecting Experiment > Pulse Voltammetry > Normal Pulse Voltammetry from the Framework™ menu bar. This initiates the following sequence of events:
1.Framework™ creates a Runner window, and the Normal Pulse Voltammetry.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. If the Advanced Pstat Setup is in the On position, a second Setup dialog box containing hardware configuration details becomes the active window, allowing you to modify the hardware configuration used during the experiment.
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.If you selected a purge time greater than zero, the potentiostat's control bits for purge-gas flow and stirring are turned on. The script delays for the purge time, then turns OFF the stirring and purge-gas control bits.
5.If the electrode is an HDME, a new drop is formed by momentarily activating the potentiostat's New Drop control bit.
6.The script delays for a time set by the Quiet Time parameter.
7.The potentiostat is initialized. The current range is set to a range that allows the measurement of currents as big as the value of the Max Current Setup parameter.
8.The potential is set to Initial E and the cell is turned on.
9.If the Equilibration Time parameter is greater than zero, the script delays for set value.
10.The actual scan occurs.
11.The potential of the sample is set to the Initial E. At the end of this time, a current measurement is made. If the electrode in use is a SMDE or DME, the mercury drop is dislodged.
12.The Initial E is applied to the cell during the initial stages of the second (and subsequent) current measurement. After a time equal to (Sampling Period – Pulse Width), a pulse of magnitude (Step Size) is applied to the electrode. The voltage step sign is controlled so that the pulse is always in the direction of the final potential. This voltage pulse is held for one Pulse Width. At the end of this time, a current measurement is made. If the electrode in use is an SMDE or DEM, the mercury drop is dislodged.
13.If Auto-ranging was selected in Setup, after each point, the current range is automatically switched to the optimal range for the measured cell currents.
14.Steps 12 and 13 are repeated until the potential prior to the pulse equals the final potential.
15.The cell is turned off. The acquired data are written to the output file. The script pauses to allow you to view the curve you have just collected. Close the curve by clicking the F2-Skip button before attempting to open the data file in the Echem Analyst 2™.