Figure 6.

Evolution of the pre-edge of r-TiO₂ upon formation of at the Ti K-edge. The spectra are calculated for a Ti atom in the bulk structure supercell (black curve), with at the apical (blue curve) or the equatorial position (red curve). The calculations are without polarization of the X-ray field (angular average). A linear combination of the apical and equatorial O_vac spectra gives a spectrum representative of the titanium atoms surrounding the O_vac (green curve). Experimental data from r-TiO₂ nanoparticles are reproduced from Finkelstein et al. (2002 ▸) (blue circles). The spectral trace 100 ps after the excitation of r-TiO₂ (black line with circle markers) is reproduced from Budarz et al. (2017 ▸). The horizontal dashed line represents the zero signal level of the X-ray absorption transient.