Inelastic electron scattering near theKedge in Be

Abstract

The energy- and momentum-dependent cross section for 200-keV electrons scattered from thin Be foils has been measured. For energy losses within 30 V of the $K$ edge and for momentum transfers out to $q=4\mathrm{}$ ${\mathrm{\AA }}^{-1\mathrm{}}$ we compare the experimental results with a theoretical one-electron band-structure calculation which includes matrix elements. Within a few volts of the edge the results agree but then begin to deviate significantly at high energies. Many-electron excitations are proposed as a mechanism to partially account for these discrepancies.