Numerical approximation of AR-XPS spectra for rough surfaces considering the effect of electron shadowing.

A computational scheme is presented that takes into account the topography, i.e. the shadowing and hence the local emission angle of the electrons when evaluating AR-XPS data of macroscopic rough surfaces. The topography of the sample surface is supposed to be recorded by atomic force microscopy and/or opticalmicroscopy. The emitted photoelectrons are simulated based on an extension of the Beer-Lambert law that includes the shadowing, the current local emission angle, and the geometrical instrument setup. The obtained angle-resolved XPS spectra are optimized in accordance with experimental ones via a self-consistentminimization algorithmthat also allows one to determine the layer thicknesses of the corrugated sample. In order to validate the proposed numerical scheme, the simulationprogram simulationof electron spectra for surface analysis is used. An additional analysis is then performed considering only experimental data. The numerical scheme gives good agreement in simulation-simulation as well as simulation-experiment comparisons and permits a comprehensible interpretation of themeasured data. [ABSTRACT FROM AUTHOR]