Low energy (1–100 eV) electron inelastic mean free path (IMFP) values determined from analysis of secondary electron yields (SEY) in the incident energy range of 0.1–10 keV

Abstract

Since the emission of secondary electrons for any incident energy always involves the formation and emission of a cascade of slow electrons (<50 eV) the secondary electron yield (SEY) for arbitrary energies depends sensitively on the inelastic mean free path (IMFP) values at low energies (below 100 eV). This makes it possible to retrieve the information about the low energy IMFP from high energy SEY experiments. A Monte Carlo (MC) code has been developed to simulate SEY values and was employed to determine the IMFP at low energies (<100 eV). This is done by varying the energy dependence of the IMFP at low energies (<100 eV) during the MC simulation of the SEY between two extremes, calculated on the basis of the Mermin dielectric function and the Penn algorithm within the simplified single-pole approximation (SSPA). Those IMFP values that give the best χ2 fit of the simulated SEY values with experimental results are considered to be the most reliable. The described algorithm was employed for the investigation of Be, Al, Si, Ti, V, Fe, Ni, Cu, Ge, Nb, Mo, Pd, Ag, Ta, W, Pt, Au. For most materials these optimum IMFP values are found to be close to IMFP values based on the Mermin dielectric function.