Two-photon photoemission spectra of rutile TiO2 (110) surface
Abstract
We have investigated the two-photon photoemission (2PP) spectra of rutile TiO2 surface after preparation by various procedures. Nearly perfect surface is obtained by a procedure of sputtering and annealing the surface under O2 atmosphere. With 3.05 eV excitation light photoemission can be observed only from defects states that are energetically below the conduction band. The 2PP signal becomes vanishingly weak as the defect density is reduced, and the measured work function is 5.5 -- 5.8 eV. The defect density can be increased by annealing the sample in absence of O_2, irradiating the surface with energetic (500 eV) electrons, or sputtering the surface with Ar ions. In each case the near surface defect density increases and the work function decreases. We attribute the spectral changes in 2PP spectra to the selective removal of O atoms and consequent increase in the Ti^3+ defect sites.
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 2004
- Bibcode:
- 2004APS..MARD35009P