Observation of Energy Loss Processes Usually Masked by Plural Scattering of Fast Electrons

Abstract

THE technique of electron energy loss analysis has application in the study of electronic energy levels of solids and in microanalysis using energy analysing electron microscopes. Plural scattering of fast electrons (incident energy 20–100 KeV) in thin films (200–1000 Å) gives rise to spectral lines which are related to the basic excitation processes and occur at approximately integral multiples of these losses; multiple losses cannot always be distinguished from the primary loss lines. Plural scattering effects can mask excitations of low probability. As a particular example we cite the electron energy loss spectrum obtained from evaporated germanium films, where the 15.6 eV plasma loss and its multiples (31 and 46 eV) obscure the M^4,5 X-ray absorption edge at 32 eV. We show that the energy spectrum of germanium may be corrected for these plural scattering effects and this reveals structure in the spectrum at 33 eV.