Normal Pulse Voltammetry Experimental Sequence

  1. The Framework creates a runner window, and theNormal 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 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 containing hardware-configuration details becomes the active window, so you can modify the hardware configuration.
  3. The script now obtains the use of the potentiostat 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. By default, the potentiostat’s cell switch is turned Off when the potentiostat is attached to the script.
  4. All header information is written to the data files. Header information consists of the analysis tag, the time and date the experiment was started, and a list of the setup parameters.
  5. 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.
  6. The script delays for a time set by the Quiet Time parameter.
  7. If the electrode is an HDME, a new drop is formed by momentarily activating the potentiostat’s New Drop control bit.
  8. 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 I Setup parameter.
  9. The actual scan occurs.
  10. 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.
  11. 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.
  12. If Autoranging was selected in Setup, after each point the current range is automatically switched to the optimal range for the measured cell currents.
  13. Steps 11 and 12 are repeated. With each current measurement, the pulse is increased by a magnitude defined by Step Size in mV. The experiment is complete when the potential corresponding to the sum of the Initial Potential and the Pulse equals the Final Potential
  14. The cell is turned off. 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™.