The Inelastic Mean Free Path οf Electrons. Research in Budapest, Warsaw, Wrocław and Clermont-Ferrand. Brief History and New Results

The inelastic mean free path of electrons (IMFP) is an important material parameter for description of electron transport processes in solids. This parameter is particularly useful for quantifying the electron spectroscopies, in particular Auger electron spectroscopy, X-ray photoelectron spectroscopy, electron energy loss spectroscopy and elastic peak electron spectroscopy. In this work, a brief overview of the IMFP determination is presented. Generally, there are two groups of methods to determine the IMFP: (i) calculations using the theoretical model based on the experimental optical data, and (ii) calculations using theory relating the IMFP and the measured probability elastic electron backscattering from solids. Major advances in the development of the second group of methods were made in three laboratories; these advances are reviewed here. The elastic backscattering probability, in absolute or relative units, can be conveniently evaluated from the elastic peak intensity. However, much effort is needed to develop the theory for calculating the IMFP, which typically involves the Monte Carlo simulations of electron trajectories in solids. Presently, this theory and typical procedures of the spectra processing are implemented in the software package EPESWIN developed by Jablonski. In recent years, much attention is devoted to the phenomenon of the electron energy losses in the surface region of solids. Reliability of the theory of elastic backscattering is distinctly improved if this effect is taken into account