Hard and soft landing of mass selected Ag clusters on Pt(111)

Mass selected Ag/sub n/ clusters (n=1,7,19) from a secondary ion source have been deposited onto a Pt(111) substrate at low temperature. The surface and resulting cluster morphology have subsequently been characterized within the same UHV chamber by variable temperature STM as a function of cluster size, kinetic impact energy, and substrate temperature. The kinetic energy per cluster atom was found to be the decisive parameter for a controlled deposition. Noble gas buffer layers ( approximately=10 ML Ar), which were pre-adsorbed onto the surface at low temperatures, were found to efficiently dissipate the impact energy opening up the possibility of soft landing clusters with elevated kinetic energy.