On the Surface Structure Determination by AES and UPS

Abstract

The recent advances of the surface structure determination by means of Auger electron and uv-photoelectron angle-resolved spectroscopies are reviewed.
The experimental results on the Auger electron angular distributions from Al, Fe, Ni and Cu single crystal clean surfaces and from the c (2x2) -O, -S, -Se adsorbed structures on Ni (100) surfaces are shown. For anisotropic Auger emissions from both single crystal surfaces and ordered adsorbed atoms, the angular momenta of valence Auger electrons play an important role as well as the multiple diffraction effect. The very recent theoretical investigations indicate that the Auger electron angular distribution from adsorbed atoms is very sensitive to the structural parameters such as the adsorbed site and the adsorbate-substrate distance.
The dependence of the uv-photoelectron emission intensity on photon incident angle, photon energy, polarization and polar emission angle are presented and discussed for the p (2x2) -O, c (2x2) -O, c (2x2) -S and c (2x2) -CO on Ni (100) surfaces to estimate the atomic geometry of adsorbed species. It has been clear, from the comparison between experimental and theoretical results, that the calculations including anisotropies of the initial states as well as of the final states are useful to determine the bonding configuration of adsorbed species.