Inelastic scattering of electrons by absorbate vibrations in the impact scattering regime: CO on Ni(100) as an example

Abstract

We have used a formalism developed by us recently to carry out a series of calculations of electron-energy-loss (EELS) cross sections for excitations of vibrations in a $c(2\ifmmode\times\else\texttimes\fi{}2)$ overlayer of CO on the Ni(100) surface. The calculations explore impact scattering and cover a wide range of energies and scattering geometries. We examine the sensitivity of the various cross sections to the CO bond length, and also to the C-Ni distance. We also find a series of selection rules that apply to the impact-scattering problem. These are discussed and illustrated with numerical calculations of the angular variation of the EELS cross sections.