Large-angle scattering of energetic electrons from Xe: A combined theoretical and experimental approach

We study the inelastic excitations of Xe for electrons with relatively high energies (500 or 750 eV) scattered over large angles, both experimentally and theoretically. In particular, we focus on the shape and intensity of the spectra of inelastically scattered electrons at the sharp dip in the elastic cross section near 135◦ at 750 eV. Under these conditions, the first Born approximation predicts virtually zero intensity. However, in reality, measurable intensity is observed. Calculations carried out using the relativistic distorted-wave method describe the measurements reasonably well. A comparison is made between the calculations and previously published high-resolution studies. Overall agreement is quite good, especially for the lowest-energy excitations, but substantial differences are found for certain higher levels. The theory reproduces quite well the variations in intensity of the inelastic excitations for measurements near the dip in the elastic-scattering cross section, somewhat surprisingly, as the theories for elastic scattering and inelastic scattering are developed along completely different lines.