User`s guide

Electrochemistry 15
Agilent 5500 SPM User’s Guide 222
bias, probe potential and sample potential. Any one of these potentials
can be swept during cyclic voltammetry in the software.
In the most common configuration:
a Set the sample potential initially to the open circuit potential (i.e.,
the potential of the cell with the counter electrode turned off).
b Set the sample potential to be swept.
c Fix the sample bias at an appropriate value for the image mode
selected.
d Setting any of the three controls to Swp will change the label on
the sweep range control to the appropriate selection. The potential
control not set to Swp or Fix will automatically be swept.
Typically EC and SPM are used in conjunction to view surfaces under
potential control. The potential is set to a particular value and the
surface imaged to show a particular feature. Next, the cell is allowed to
return to equilibrium, the potential is changed and the surface
re-imaged, to show changes due to changing potential. These
differences are typically due to ordering of molecules on the surface
caused by changing potential.
Choosing VEC and IEC as image channels allow the potential and
current flow in the cell to be saved consecutively with the image data for
future reference.
Galvanostat
The galvanostat allows control of the sample current. The current into or
out of the working electrode is measured and the voltage of the cell is
adjusted to maintain a constant value of current flow as long as the
voltage required to do so is within ±10 V.