Elastic Scattering of Low-Energy Electrons from Surfaces

Abstract

Publisher Summary The extensive activity and progress of the last decade have clarified the important ingredients of a satisfactory understanding of the elastic scattering of low-energy electrons by surfaces. The electrons are scattered within a few atomic planes of the surface and their diffraction is intermediate between the kinematic and dynamic limits. The large cross sections for elastic scattering lead to significant multiple scattering, but for energies reasonably above the plasmon threshold the inelastic processes rapidly attenuate higher-order scattering processes. For the usual experiments, the momentum transfer is large, so the scattering is mainly sensitive to the potentials rather deep in the ion core, and the scattering factors are similar to those for free atoms. Consequently, the core potentials must be treated correctly in any realistic calculations. However, the scattering is quite insensitive to the valence electrons and the surface potential. Thus elastic scattering is primarily a tool for studying the atomic rather than the electronic structure of surfaces. Both because the momentum transfer is large and because the electrons are scattered from the surface region where thermal vibrational amplitudes are large, temperature effects are very important and must be accounted for in interpreting diffracted intensities. Low-energy electron scattering also provides the most direct technique for investigating surface lattice dynamics.