Ti and O K edges for titanium oxides by multiple scattering calculations: Comparison to XAS and EELS spectra

Theoretical simulations and interpretations of x-ray-absorption near-edge data at the Ti and O K edges in titanium oxides. rutile, and anatase, have been performed in the framework of full multiple scattering theory and a tight-binding Linear muffin-tin orbital band-structure method. Good agreement between experimental data and theoretical calculations is obtained, especially in the preedge region of the Ti K-edge spectrum which is interpreted in terms of mixing between the central Ti 4p and neighboring Ti 3d orbitals in octahedral coordination. It is concluded that the positions of these latter Ti atoms relative to the photoabsorber influence in a noticeable way the intensity, width, and position of the features in the preedge region, which mainly originate from dipole transitions. Previous work on the subject is reexamined in the light of the present findings.