Adsorption states of size-selected Pt7 clusters soft-landed on an Al2O3/NiAl(1 1 0) were investigated using scanning tunneling microscopy and spectroscopy at 300 K. Pt-7 clusters lay flat on the surface with a planar structure and were preferentially adsorbed on domain boundaries (DBs) of the Al2O3 film. Because the clusters are thermally immobile, adsorption to DBs is controlled by transient mobility on the surface. The mean lateral displacement by transient migration is estimated to be similar to 8 nm. Distinct conductivity resonances through unoccupied states of the Pt7 clusters were observed near 2 V. (C) 2013 Elsevier B.V. All rights reserved.