Simultaneous determination of composition and thickness of thin iron-oxide films from XPS Fe 2p spectra

The composition and thickness of thin iron-oxide films on pure iron were determined from XPS Fe 2p spectra. To this end the spectra were reconstructed from reference spectra for Fe-0, Fe2+ and Fe3+. The appropriate background due to inelastically scattered electrons was calculated for each reference spectrum, using a recent generalization of Tougaard's method. For the reconstruction the film thickness and the relative amounts of Fe2+ and Fe3+ in the oxide film were used as fit parameters. A good agreement was obtained between experimental and reconstructed spectra.