An empirical treatment of fast-electron scattering in semi-infinite targets

A simple empirical treatment is given of the absorption of fast electrons and their energy at normal incidence in semi-infinite targets. It is based on the consideration of the multiple reflection of electrons at imaginary planes parallel to the surface. Experimental data measured on films of various thicknesses for transmitted and backscattered electrons can be used for calculations for semi-infinite targets. Analytical expressions are also set up to describe the behaviour of electrons transmitted through or backscattered from a film. From these it is possible to analyse the multiple reflection of 10-100 keV electrons for nearly all elements. As an application, the energy dissipation is calculated for 20 keV electrons in copper and gold, and the results are compared with those of other investigators. The present values resemble those calculated by Spencer and by Bishop.