).The adsorption of a submonolayer of catechol (C6H6O2) on the rutile TiO2(110)-1x1 surface has been investigated by Scanning Tunneling Microscopy (STM). The catechol molecules are preferentially adsorbed on the surface 5-fold coordinated Ti4+ sites, and occupy two neighboring lattice Ti sites. No preference for adsorption at surface step edges is observed at room temperature. A statistical analysis of intermolecular distances demonstrates that the interaction between the molecules strongly depends on the surface crystallographic direction: catechol molecules exhibit attractive interaction along [1-1 0], while they repel each other along the [001] direction. The attractive interaction is proposed to be caused by the coupling of pi bonding electrons and the repulsive interaction is possibly mediated by substrate.
Reprints available from U. Diebold (diebold).
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