Using grazing incidence surface X-ray diffraction, the superstructure of TiO2(100)-(1 x 3) (rutile) was investigated. The analysis of both fractional order superlattice rods and integer order crystal truncation rods (229 independent reflections in total), led to a structural model which could basically be described as the formation of {110} micro-facets on the surface. In addition, strong lateral and vertical relaxations of the titanium and oxygen atoms exist down to about 9Å below the surface. The surface titanium atoms were found to reside in different environments, namely in three-, five- and six-fold oxygen coordination and in a bridge site. Furthermore, a 40% occupancy was determined for an interstitial site occupied by one titanium atom per (1 x 3) unit cell. The surface stoichiometry was given by the formula TiO1.68. The structural model was significantly different to previous X-ray data, but was in good agreement with spectroscopic experiments and scanning tunnelling microscopy investigations.

Surface X-Ray Structure Analysis of the TiO2(100)-(1 x 3) Reconstruction. Zajonz, H., Meyerheim, H.L., Gloege, T., Moritz, W., Wolf, D.: Surface Science, 1998, 398[3], 369-78