Vacant states of TiO2 with rutile structure and their reflection in different-type x-ray absorption spectra

A tight-binding linearized muffin-tin orbital method was applied for the calculation of the densities of states (DOS) for TiO2 with the rutile structure in the wide energy region of the conduction band. The calculated partial DOS of titanium and oxygen were compared with the experimental Ti 2p total electron yield spectrum (TEY), which was measured in the present work, and the Ti Is x-ray absorption spectrum, O 1s TEY and bremstrahlung isochromat spectrum taken from the literature. We found that in the energy region higher than similar to6 eV above the bottom of the conduction band the fine structure of experimental absorption spectra follows the distribution of the corresponding partial DOS. In connection with this, one does not need to use any satellite mechanism for an interpretation of these spectra. In the region of vacant Ti 3d states (up to similar to6 eV), correspondence between the experimental and calculated splitting of t(2g), and e(g) subbands is observed in all spectra except Ti 2p TEY. As we showed using atomic calculations, this is connected with the Ti 2p(5)3d(1) multiplet in the final state of absorption which leads to suppression of the intensity of lower states of the t(2g) subband in Ti 2p TEY of TiO2. As a result, t(2g)-e(g) splitting extracted from Ti 2P(3/2) and Ti 2p(1/2) TEY is less than in Ti 3d DOS and other experimental spectra (Ti 1s XAS and O 1s TEY) in which an interaction of core level vacancy with photoelectron is absent owing to the delocalized character of valent states. Copyright (C) 2002 John Wiley Sons, Ltd.