Energy dependence of interference phenomena in the forward-scattering regime of photoelectron diffraction

X-ray photoelectron diffraction is a powerful spectroscopic technique in the direct legacy of C.S. Fadley that combines high sensitivity to the arrangement of atoms in crystals and element specificity providing unique fingerprints of selected atomic sites in matter. When used with kinetic energies between 500 eV and 1500 eV, its interpretation and description is based on the fact that the atomic scattering factors are strongly forward-peaked in such a way that low-angles scattering and backscattering events are respectively dominant and almost irrelevant in the photoemission process. In this paper we aim to demonstrate with the help of multiple-scattering simulations that energy scans of high-energy (500–1500 eV) forward-scattering photoelectron diffraction can provide valuable structural and chemical information about thin epitaxial films or stacking of two-dimensional materials.