User`s guide

213
Agilent 5500 SPM
User’s Guide
Agilent Technologies
15
Electrochemistry
Equipment 216
Liquid Cell 216
Electrodes 216
Working Electrode and Pogo Electrode 216
Reference Electrode 217
Counter Electrode 217
Cleaning 218
Liquid Cell Cleaning 218
Non-Critical Applications 218
Critical Applications 218
Electrode Cleaning 219
Sample Plate Cleaning 219
Substrate Cleaning 219
Assembling and Loading the Liquid Cell 219
Troubleshooting 220
Electrochemistry Definitions 220
Software Controls 221
Potentiostat 221
Galvanostat 222
The electrical potential that exists across the interface between a metal
surface and an electrolytic solution is known as the “surface potential.”
This is the driving force behind such processes as adsorption, desorption
and electron-transfer reactions. Quantifying and controlling this
potential is the science of electrochemistry.
Metal electrodes placed into an electrolytic solution will register a net
potential composed of two unknown potential drops, one across each
electrode-electrolyte interface. A third, chemically reactive reference
electrode is maintained in equilibrium with the ions in solution that are
oxidized and reduced at its surface. To maintain this equilibrium, the
concentrations of reactants must be held constant at the electrode
surface, as is true when negligible current flows through the reference
electrode.
Figure 145 shows a typical electrochemistry setup, while Figure 146
shows that same setup created with the 5500 SPM liquid cell. Note that