Optical Properties of Single-Crystal Anatase TiO_<b>2</b>

Abstract

Polarized Reflection spectra of single-crystal anatase TiO 2 were measured in a photon energy range from 2 to 25 eV using synchrotron orbital radiation. Dielectric constants and absorption spectra were obtained from reflection spectra by Kramers-Kronig transformations. To interpret the structures that were observed in the spectra, the electronic states of anatase were calculated by using a cluster model with a size of Ti 5 O 14 . The structures observed in the energy region from 3 to 12 eV can be identified primarily due to the transition from O(2 p ) orbitals to Ti(3 d ) ones. The polarization dependence of the spectra in the above energy region is also effectively exhibited by the calculations from this model. The vague structures in the higher energy region (>12 eV) which can be clearly distinguished in spectra from the low energy part are due to the transition from O(2 p ) orbitals to Ti(4 s , 4 p ) ones.