MEDIUM-ENERGY BACKSCATTERED ELECTRON-DIFFRACTION STUDIES OF TIO2(110) - RELATION TO SURFACE-STRUCTURE

Medium-energy backscattered electron diffraction (MEED) studies are reported for the rutile TiO2(110) surface. Two-dimensional diffraction images are obtained using a retarding field analyzer with a microchannel plate-intensified detector. Background removal is accomplished using digital image processing techniques. We find that the backscattered pattern for 750 eV incident electrons is predominantly due to diffraction of the outgoing electrons (subsequent to backscattering from subsurface atoms) by overlying lattice atoms. We also find effects related to the orientation of the incident beam relative to the surface. These effects are ascribed to diffraction of the incoming electrons (prior to backscattering) and possibly the focusing of electron intensity on second-layer atoms. Single-scattering cluster (SSC) calculations are used to model the outgoing diffraction process. The results are qualitatively consistent with a bulk-like termination of the TiO2(110) surface.