Abstract :
AES and XPS are two powerful techniques for the determination of the composition of a surface. The nature of the
chemical binding of an element is usually studied by XPS. However, the Auger peaks also contain theoretical information
about the chemical environment of the elements. As mostly one or two valence levels are involved in the emission of the
Auger electron, a careful analysis of the Auger lines should allow to reveal the changes in the electron densities in the
electronic levels due to a change in the chemical environment. However, for metals with a high number of electrons.the
chemical effects are mostly weak, hidden or hard to interpret. In order to try to understand better the nature of the chemical
effects in AES of metals, a systematic study of well-defined copper compounds is performed. Cu, CuO, Cu2O, CuCO3and
copper acetate standard samples were prepared and characterised. The copper LMM lines were analysed. The energy shifts,
change in relative intensities and change in FWHM were studied as a function of increasing oxygen environment. We show
that the energy shift and the relative intensities of the Auger peak are good fingerprints of the oxidation state, and that the
width of the Cu L3M4,5M4,5 peak can be related to the width of the valence band. q1999 Elsevier Science B.V. All rights
reserved.
