We have studied the growth mode and morphology of Ni clusters on a TiO 2 (110) surface with a wide terrace using scanning tunneling microscopy (STM) at a low coverage (less than 3 atoms nm Above the coverage of 1.0 atoms nm -2 , an increase in the cluster height occurs, retaining an almost constant lateral size. It is proposed that the interaction of the Ni cluster and the support surface regulates the Ni cluster size.

The structure of low coverage Ni atoms on the TiO2(110) surface was studied using polarization dependent EXAFS. We found that Ni atoms interacted with oxygen atoms at the n 1 1 step edges, where atomically dispersed Ni species were found with Ni-O distances at 0.199 ± 0.002 nm and 0.204 ± 0.003 nm in parallel and perpendicular directions to the Koike et. al. 2 TiO2(110) surface, respectively. The location corresponded to the virtual Ti site if the next TiO2 layer was created on the topmost TiO2 surface. The Ni location is mainly determined by the dangling bond directions of the surface oxygen atoms.

(pictogram)On a bare TiO 2 (110) surface Cu easily aggregates to Cu particles by vacuum evaporation while on the TiO 2 (110) surface premodified with 3-thiophene carboxylic acid provide monoatomically dispersed Cu species which will lead to small nanocluster with less than 1 nm in size.

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Three-dimensional structures of Ni clusters deposited on a TiO2(110) surface were studied using polarization-dependent total reflection fluorescence X-ray absorption fine structure (PTRF-XAFS) analysis. Three-dimensional Ni clusters were formed with a slightly anisotropic structure at 1 × 1014 atoms/cm2. The PTRF-XAFS results for a 1 × 1014 atoms/cm2 sample revealed the formation of one-atomic-layer Ni clusters with a distorted (110)fcc plane structure. We found a Ni−Ni distance of 0.240 nm with Ni−O interaction at 0.23 nm. The structure was stabilized by interaction of surface oxygen atoms. The origin of cluster size self-regulation was the strong Ni−O interaction and matching of the crystal lattice between TiO2(110) and distorted Ni(110) structures.