QUEELS software package for calculation of surface effects in electron spectra

Abstract

AbstractSurface analysis based on the interpretation of electron spectroscopy such as x‐ray photoelectron spectroscopy, Auger electron spectroscopy, or reflection electron energy loss spectroscopy are influenced by the inelastic scattering processes that take place when an electron moves in the region near a solid surface. The actual energy losses depend on the particular experimental situation. Thus, an electron is attracted by its image charge when it is moving in the vacuum. It will therefore lose energy even after it has left the surface and, similarly, an electron that moves in the vacuum towards the solid surface gains energy. Likewise, the scattering properties for an electron moving close to the surface are different from those of an electron moving in the bulk of the solid. In photoemission and Auger experiments the effect of the static hole will also affect the scattering probabilities of the electron in the first few ångströms as it moves away from the point of excitation. These effects will also cause the ‘effective’ inelastic mean free path to depend on the position of the electron with respect to the surface and with respect to the point of excitation. In the past years, we have developed models to describe these effects within a dielectric response theory for different cases of electrons moving near surfaces in general geometries with or without a static core hole. The formulas are quite involved with many infinite integrals and this is a major barrier for people to apply them in practice. With the purpose of making the calculations easier to perform, we have developed software (QUEELS: QUantitative analysis of Electron Energy Losses at Surfaces) that will do this in a user‐friendly way. It is hoped that with this tool at hand, we will be able to more effectively and quickly get a more complete understanding of the importance of these different effects for quantitative analysis of surface electron energy spectra. Copyright © 2004 John Wiley & Sons, Ltd.