Chemical information from XPS—applications to the analysis of electrode surfaces

Some of the difficulties in using x‐ray photoelectron spectroscopy (XPS) for the chemical characterization of surfaces are considered. XPS chemical shifts are often quite small, compared to spectral line widths and to the accuracy of the reference data. Moreover, subtle differences in peak shape are often degraded by inadequate counting statistics. However, progress toward better chemical characterization is being made by using rigorous peak‐fitting routines and correlating chemical shift information from several photoelectron and Auger electron lines. This paper describes two examples of these procedures in the study of electrode processes: (1) the use of multiple line shifts to follow the evolution and growth of different copper oxide phases during anodic polarization of a copper–metal electrode; (2) the use of peak‐fitting routines to determine stoichiometric changes on a UO2 electrode surface with good precision.