INELASTIC SCATTERING IN LOW-ENERGY ELECTRON DIFFRACTION FROM SILVER

In a low-energy electron diffraction experiment on Ag (111) we have studied the inelastically scattered current of electrons having lost 10 eV. We show quantitatively that this current, which is strongly peaked in the directions of Bragg reflections, arises from a two-step process involving both an elastic and an inelastic scattering. A model based on the two-step process is developed and then compared with experimental results. The model allows one to separate the Bragg and phonon components of the inelastic scattering and to extract an energy-loss spectrum which is independent of the elastic scattering. The structure, intensity, angular widths, and angle-of-incidence dependence of the energy-loss spectra are compared with the predictions of a dielectric-constant energy-loss formalism using known optical constants. The comparison, which includes both surface and volume losses, shows reasonable agreement and indicates that the surface losses predominate. © 1969 The American Physical Society.