Angle-resolved electron-energy-loss spectroscopy: Atomic-core excitations at adsorbates on surfaces.

Abstract

By treatment of the incident and detected electron states in a LEED formalism, it is shown that the dominant processes contributing to a surface electron-energy-loss fine-structure (SEELFS) spectrum from atomic adsorbates on crystal surfaces are those involving elastic backscattering and small-angle inelastic scattering. This justifies the use of the ``dipole approximation'' for the atomic matrix elements in the interpretation of SEELFS. The angular dependence of the detected electrons is calculated for the first time and its potential for surface structure determination discussed.