Inelastic background analysis of HAXPES spectra: towards enhanced bulk sensitivity in photoemission

We report on quantitative inelastic background analysis in hard X‐ray photoelectron spectroscopy at high excitation energy (12–18 keV) using the Tougaard method implemented with careful optimisation of the inelastic scattering cross section. Such a method enables the determination of the in‐depth elemental distribution over depths up to70 nm. We studied three parameters and investigate their influence on the results: the depth of the layer increases the uncertainty, the thickness and composition of the layer has an influence on statistics, and the excitation energy that must be chosen as a trade‐off between high probing depth and low photoionization cross section. We show how this promising method can be used to follow diffusion of a 1‐ML La layer after annealing a technologically relevant sample.