Quantitative analysis of the inelastic background in surface electron spectroscopy

Abstract

AbstractRecent progress, in the quantitative analysis of the distortion of surface electron spectra, resulting from inelastic electron scattering, is reviewed.A physical model for the problem is formulated and based on this, basic deconvolution formulae are found. In the formulae, detailed information on the differential inelastic electron scattering cross‐section K is essential. Methods to determine,K are studied and developed. One method is based on a dielectric response calculation. Furthermore, it is found that for the noble and transition metals, K is sufficiently similar that a simple ‘universal’ cross‐section can be defined. In addition, methods for experimental determination of cross‐sections are found and in particular a formula is derived which allows the extraction of direct quantitative cross‐section information through a simple analysis of REELS spectra.The importance of proper background correction is investigated for model electron spectra. Experimental XPS spectra are also studied and it is found that for both the simple and the noble metals, the primary excitation spectra extend 2–3 inelastic scattering events, i.e. ∼50 eV, below the peak energy. Beyond this energy, the spectra are of zero intensity over a wide energy range. Besides, experimental spectra are analysed on the basis of experimentally determined cross‐sections and the results are discussed, in relation to the analysis based on theoretical cross‐sections.The importance of defining simple procedures for routine analysis of spectra is stressed and it is demonstrated that the proposed ‘universal’ cross‐section provides a very simple method for approximate spectral analysis.Finally, some important issues to be considered in the near future are pointed out.