Inelastic Scattering of Low Speed Electrons from a Copper Single Crystal

Abstract

The energy distribution of inelastically scattered electrons from a (100) face of a copper single crystal has been investigated by the electrostatic deflection method. Using normal incidence of the primary electrons, observations were made in the neighborhood of two strong diffraction peaks in the (100) azimuth, one at 59.5-ev primary energy and colatitude angle 60°, and one at 114.5 ev and 40.5°. Discrete loss peaks were observed at about 3.0-, 6.0-, 12.3-, and 20.0-ev energy loss with the intensities depending on both primary energy and colatitude angle. An excess of inelastic scattering occurs near the elastically scattered diffraction beams so that maxima are observed in the curves giving the intensity of inelastic scattering as a function of primary energy for constant values of energy loss. Near the 59.5-ev diffraction beam the maxima of the curves for different values of energy loss occur at a constant value of primary energy. This suggests that the inelastic scattering takes place after diffraction, but the fact that the maxima occur at 56 ev instead of 59.5 ev is not understood. For inelastic scattering near the 114.5-ev diffraction beam the results are complex but are approximately explained by assuming (1) inelastic background scattering followed by diffraction, for energy losses below 10 ev, (2) the same as (1) plus diffraction followed by inelastic background scattering, for energy losses above 10 ev. Possible reasons are given for the fact that the maxima for the latter process occur 3.5 ev above the energy for the diffraction maximum.