Surface defects of TiO 2(110): A combined XPS, XAES AND ELS study

Abstract

Intrinsic defects were produced at TiO 2(110) by thermal treatment and ion bombardment. High-temperature low-oxygen-pressure treatment leads to the formation of point defects with characteristic shifts in the cation (Ti 2p and Ti 3p) core levels of 1.7 eV towards lower binding energies and in the anion (O 1s) core level towards higher binding energy. Simultaneously, attenuation of nonbonding O 2p valence band states, an additional auger peak at 5.3 eV higher energy than the L 3M 23V transition of ideal surfaces without point defects, and a pronounced electronic loss feature at 0.8 eV are observed. From these results, a defect-related gap state with mainly Ti3d contribution 0.3 eV below the conduction band edge can be determined.