### Session X40: Focus Session: Morphology and Evolution at Surfaces: Defects and Transport

8:00 AM–10:12 AM, Friday, March 25, 2005
LACC Room: 408A

Chair: Katsuyo Thornton, University of Michigan

Abstract ID: BAPS.2005.MAR.X40.7

### Abstract: X40.00007 : Surface defect-promoted interaction of TiO$_2$(110) with molecular oxygen

9:12 AM–9:24 AM

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#### Authors:

Ken Park
(Department of Physics, Baylor University)

Minghu Pan
(Department of Physics and Astronomy, University of Tennessee)

Vincent Meunier
William Shelton
(Computer Science and Mathematics Division, Oak Ridge National Laboratory)

Sergei Kalinin
We present recent results on the local interactions between surface defects on a TiO$_{2}$(110) and their reactivity with oxygen studied by a combination of Scanning Tunneling Microscopy and Spectroscopy. High-resolution STM images, interpreted with first-principles theory, show that the observed one-dimensional strands have partially reduced Ti atoms coordinated at oxygen octahedral sites forming edge-sharing octahedra. When strands are exposed to 5 x 10$^{-7}$ Torr O$_{2}$ at 300 K, oxygen is adsorbed and preferentially nucleated on and along the strands, indicating the presence of exposed Ti ions. The exposure to molecular oxygen also results in oxygen adsorption at Ti$^{4+}$ sites on (1x1)-terminated terraces. The adsorbed oxygen species result in dark defective''features in STM, identical to those on the pristine TiO$_{2}$(110), and further diffuse on the surface. The implications of this behavior and specific interaction between defects and gas molecules for catalytic activity are discussed.