The effect of plasma oscillations on the inelastic scattering spectrum of a fast electron in metals

Using the Nozieres-de Dominicis-Langreth theory the effect of plasmons on the structure and features of the dynamic formfactor describing the scattering of a fast electron with a transition of an internal electron from an atomic level onto the Permi surface is investigated. Neglecting dispersion of the plasmons an expression is obtained for the dynamic formfactor which explains the features of the spectrum due to plasmons. It is shown that the probability of an (e, e')-process W(q,ω)depends to a large extent on the sign of the exponent of the energy factor a(1). For a(l)< 0 the function W(q,ω) is a decreasing function of ω,which vanishes when ω = ω(n) = ω + а ω(p) + n ω(p), when а(l)> 0 the function W(q,ω) has a singularity of the type (ω—ω(n))^(-α(β)). These features are important when a fairly wide range of the transmitted energy spectrum is being investigated.