Calculations of electron inelastic mean free paths from experimental optical data

Calculations are reported of inelastic mean free paths (IMFPs) for 100–2000 eV electrons in C, Mg, Al, Al 2 O 3 , Cu, Ag, Au, and Bi from experimental optical data. These calculations require knowledge of the momentum‐transfer dependence of the differential scattering cross section; this information was taken from Penn's calculations. The calculated IMFPs agree reasonably with direct calculations and with measured electron attenuation lengths (ALs). Since accurate measurements of ALs are difficult, it is suggested that calculations of the present type are useful if the needed optical data are available. The present approach is also useful for materials (such as the transition and noble metals) for which it is not possible to make a meaningful distinction between valence‐electron and core‐electron excitations as required in current IMFP calculations. The dependence of the calculated IMFPs on electron energy varied with material and was associated with different spectral distributions of the electron energy‐loss function. The trend in the dependence of IMFP on energy was similar to that found in analysis of AL data.