AVS 49th International Symposium
    Surface Science Tuesday Sessions
       Session SS3-TuM

Paper SS3-TuM10
Electronic and Geometric Structure of Anatase TiO@sub 2@(101) and (001) Single Crystals

Tuesday, November 5, 2002, 11:20 am, Room C-112C

Session: Metals, Adsorbates, and Defects on TiO@sub 2@
Presenter: R.L. Stockbauer, Louisiana State University
Authors: A.R. Kumarasinghe, UMIST, UK
W.R. Flavell, UMIST, UK
A.G. Thomas, UMIST, UK
A.K. Mallick, UMIST, UK
D. Tsoutsou, UMIST, UK
G.C. Smith, UMIST, UK
R.L. Stockbauer, Louisiana State University
M. Grätzel, Swiss Federal Institute of Technology
R. Hengerer, Swiss Federal Institute of Technology
Correspondent: Click to Email
Scanning tunnelling microscopy (STM), low energy electron diffraction (LEED) and resonant photoemission studies on single crystal anatase TiO@sub 2@ (101) 1x1 and (001) 1x4 surfaces are reported. The (101) surface exhibits triangular shaped large terraces/steps leading to a saw tooth like structure. The steps are monatomic and are ~ 4Å high. Atomically resolved STM images show that the (101) surface has a bulk (1x1) termination and is unreconstructed. Defect states which are clearly observed in atomica lly resolved images can be created on clean (101) surfaces following sputter anneal cycles. Bright features are seen on atomic rows are most likely due to adsorbed molecules.@footnote 1@ A defect peak is observed near 1 eV BE in UPS and is thought to arise from the loss of surface oxygen. This state is investigated using I/V measurements from scanning tunnelling spectroscopy (STS). Ti 3p-3d resonant photoemission of the surfaces are compared with earlier work from rutile TiO@sub 2@ (110) and features in the valence band at around 6 and 8 eV BE are assigned regions of weak and strong Ti-O hybridisation respectively. The defect peak is observed at around 1 eV BE for both surfaces following surface defect creation and is thought to arise from Ti@super 3+@. This peak can be removed by gentle heating in oxygen.@Footnote 2@ Constant initial state spectroscopy reveals differences in cation-anion hybridisation between the two surfaces, while repeated sputtering shows the (001) surface to be more resistant to the creation of O vacancies than the (101) face. @FootnoteText@ @footnote 1@ W. Hebenstreit, N. Ruzycki, G. S. Herman, Y. Gao, and U. Diebold, Phys Rev B, 62, 24, (2000).@footnote 2@ A.G. Thomas, W.R. Flavell, A.R. Kumarasinghe. A.K. Mallick. D. Tsoutsou, G.C. Smith, R. L. Stockbauer, M. Grätzel and R. Hengerer (in preparation).