Electron excitation and the optical potential in electron microscopy

Abstract A theory for inelastic scattering of fast electrons in solids is developed, based on an extension of the theory of scattering in an electron gas. Values of the inverse mean free path and related optical potential can be computed quite conveniently. It appears that, particularly in the case of solids characterized by high atomic numbers, the contribution of inelastic scattering to the optical potential for fast electrons may have been considerably over-estimated by electron microscopists in the past.