VIRTUAL SCATTERING OF HIGH-ENERGY ELECTRONS BY PLASMONS AND VALENCE-ELECTRONS IN SILICON

The contribution from plasmon and valence-electron scattering to the h igher-order Fourier coefficients of the electron virtual scattering po tential (EVSP) is shown to be non-negligible in contradiction to previ ous assumptions. In particular, calculations are made for this contrib ution to the EVSP C-0.g(r)(plasmon) for g = 111 in silicon. In contras t to the elastic potential, C-0.g(r)(plasmon) is found to be highly en ergy dependent, varying by three orders of magnitude between 20 eV and 100 keV. Whilst it is found that the contribution from plasmon scatte ring is larger than that from tightly bound core states, the relative contribution to the total potential is smaller than that presently res olvable by electron experimental methods at 100 keV.