ANGLE-RESOLVED INVERSE-PHOTOEMISSION STUDY OF THE NEARLY PERFECT TIO2(110) SURFACE

We present angle-resolved inverse-photoemission (IPE) spectroscopy dat a from the nearly perfect TiO2(110) surface. Results from two high-sym metry directions of the surface Brillouin zone, GAMMABAR-XBAR and GAMM ABAR-XBAR', are reported and compared with the results of bulk and sur face electronic-structure calculations. Features in the spectra appear ing approximately 1, 4, 9, and 13 eV above the Fermi level are associa ted with the primarily Ti-derived 2t2g, 3eg, 3a1g, and 4t1u levels. Th e results are consistent with earlier studies using x-ray-absorption s pectroscopy and electron-energy-loss spectroscopy but show some discre pancies in energy positions. All of the spectral features exhibit a sm all amount of dispersion with respect to k(parallel-to). Surface state s and resonances identified in the 0-2-eV region are in accordance wit h previously published calculations [S. Munnix and M. Schmeits, Phys. Rev. B 30, 2202 (1984)]. The absence of surface resonances near 3 eV s trongly suggests that the nearly perfect TiO2(110) surface is terminat ed by a bridging oxygen layer.