Ru Estimation Setup Parameters

Click on each of the setup parameters for a description of its use and function.

Pstat Selects the potentiostat/galvanostat that will perform the experiment. Each labeled button corresponds to an installed potentiostat. When you select a potentiostat, its corresponding button is filled in. In a multiple-potentiostat system, you can change the potentiostat selection by clicking on a Pstat’s button using the mouse. From the keyboard, you tab down until a dotted line appears around one of the Pstat labels, then hit the spacebar to select among the potentiostats. You can select only one potentiostat at a time, so selecting one potentiostat de-selects another one.
DC Voltage

Defines the constant potential applied to the cell during the impedance measurement.

The DC Voltage is entered in volts. The voltage can be entered as being absolute (vs Eref radio button) or relative to the open-circuit potential (vs Eoc radio button).

Estimated Z

A user-entered estimate of the cell's uncompensated resistance. It is used to limit the number of trials required before acquiring the first data point in an impedance spectrum.

Before taking the first data point, the script sets up the potentiostat and FRA to measure an impedance equal to Estimated Z and tries to measure the cell's uncompensated resistance. If the estimate is fairly accurate, the first (or second) attempt to measure the impedance succeeds. If the estimate is poor, the system may take several trial readings before it finds the correct settings.

The units for Estimated Z are ohms. There is no reason to enter values larger than 1 TΩ or smaller than 0.01 Ω, because these values drive the system settings to their most sensitive and least sensitive settings, respectively.