ABSTRACT
The simulation of the electrochemical double layer under ultrahigh vacuum (UHV) conditions allows the characterization of the chemical interaction between electrode surface and electrolyte constituents. The electron work function measured for an adsorbate covered metal in UHV is considered to be equivalent to the electrochemical potential for the same adsorbate-electrode pair in solution. This common potential scale represents an important link between UHV studies and electrochemistry. The potential range accessible by the investigation of substrates with different work functions can be expanded by the coadsorption of electronegative and electropositive species, such as halogens or alkali metals, which induce large work function changes. The adsorption of anions or cations from electrolytes, achieved in UHV at low temperature, is of particular interest. Solvation processes and surface reactions, which result from the electrostatic interaction between the partially ionically adsorbed species and coadsorbed H2O, the most frequently used solvent, can be studied by applying surface sensitive techniques. A variety of methods have been developed that allow the investigation of the surface structure and chemical composition.
