NA ADSORPTION SITES ON TIO2(110)-1X2 AND ITS 2X2 SUPERLATTICE

Scanning tunnelling microscopy (STM) has been used to investigate the structures formed by a low coverage (< 0.01 ML) of Na on reduced 1 x 2 surfaces of TiO2(110). The STM images recorded at positive sample bias indicate that Na adsorbs in three-fold coordinated sites adjacent to the bridging-O row; forming a p(4 X 2) overlayer. Adsorption on areas of the clean surface which contain the 2 X 2 superlattice suggest that Na adsorbs in a site with a four-fold coordination to oxygen. This is accompanied by Na-induced substrate restructuring.