Scattering Factors and Other Properties of Low-Energy Electron Diffraction

Abstract

Improved low-energy electron diffraction equipment which yields better resolution and a proper background is described. The equipment is sufficiently flexible for measurements of total elastic and inelastic backscattering, and this is illustrated with several examples. Elastic and inelastic scattering factors are considered and illustrated by experimental data. Since they are complex, complicated, and only semiquantitatively understood, precise surface structure analysis is generally not possible at the current stage of development of this technique, though it now provides a very powerful method for characterizing surface structures. Various approximate methods for interpreting diffraction data are outlined. A preferred approach to a dynamic theory is also discussed. Other physical properties such as Fresnel zone corrections, Lorentz factors, effects of contact potential, properties of diffraction by two-dimensional gratings, properties of averages, specimen orientation effects, effects of steps, and thermal disorder are considered and illustrated. The analytical results for x-ray and high-energy electron diffraction are sueful but sometimes not directly applicable.