Theoretical study of the surface excitation parameter from reflection-electron-energy-loss spectra

A theoretical method to determine the so-called surface excitation parameter (SEP) is presented. This method is based on the modelling of reflection-electron-energy-loss spectroscopy and more particularly on the analysis of energy-differential inelastic electron scattering cross sections calculated within the model. The SEP is extracted from theoretical cross-section spectrum by calculating the ratio between the surface loss component of the spectrum and the elastic peak intensity. The calculations have been performed entirely with the dielectric function, using the software QUEELS (Quantitative analysis of Electron Energy Losses at Surfaces) recently developed by Yubero and Tougaard [Surf. Interface Anal. 2004; 36: 824]. The angular distribution of SEP is calculated for angles between 10 degrees and about 70 degrees for aluminium and silicon. We propose also an extension of the method for materials (e.g. copper) that do not present clear surface and volume plasmons. Copyright (C) 2005 John Wiley & Sons, Ltd.