Titanium and titanium oxides at the K- and L-edges: comparing theoretical calculations to X-ray absorption and X-ray emission measurements

Abstract

Using well-calibrated experimental data we demonstrate the applicability of theoretical X-ray absorption spectroscopy (XAS) as well as X-ray emission spectroscopy (XES) calculations for titanium (Ti), titanium oxide (TiO), and titanium dioxide (TiO₂) at the Ti K and L edges as well as O K edge. XAS and XES in combination with a multi-edge approach offer a detailed insight into the electronic structure of materials since both the occupied and unoccupied states are probed. The experimental results are compared with ab initio calculations from the OCEAN package which uses the Bethe–Salpeter equation (BSE) approach. Using the same set of input parameters for each system for calculations at different edges, the transferability of the OCEAN calculations across different spectroscopy methods and energy ranges is demonstrated. Thus, the broad applicability for analyzing and interpreting the electronic structure of materials with the OCEAN package is shown. While the results showed that the OCEAN package is a useful tool for analyzing and interpreting the electronic structure of materials, it also highlighted some discrepancies between the experimental data and the theoretical calculations, indicating some limitations of the approach.