Small, uniform, and thermally stable silver particles on TiO2(110)-(1x1)

We have investigated the growth of silver islands on TiO2 (110)-(1 x 1) by scanning tunneling microscopy (STM). For room-temperature deposition of coverages between 0.05 and 1.0 ML, small, three-dimensional islands with a narrow diameter distribution are formed. The observed behavior is qualitatively similar to the 'self-limiting' growth previously reported for Cu on the (110) surface of titania (rutile). That is, above about 0.5 ML, the average Ag island diameter is nearly independent of coverage and island nucleation continues up to 1 ML in coverage. However, at the same coverage, the density of Ag islands is roughly half that of Cu islands and the Ag islands are larger, differences resulting from the higher mobility of Ag compared with Cu. The Ag islands are remarkably stable under thermal annealing - long-term or high-temperature annealing increases the island diameter by less than a factor of two. Strikingly, the island densities for annealed adlayers are nearly independent of coverage above 0.25 ML. (C) 2000 Elsevier Science B.V. All rights reserved.