Growth modes of thin films of ligand-free metal clusters

Abstract

Size-selected Mon−, Wn−, and Fen− cluster anions are deposited on a weakly interacting substrate (highly oriented pyrolytic graphite) and studied ex-situ using atomic force microscopy. Depending on size, three growth modes can be distinguished. Very small clusters consisting of less than 10–30 atoms behave similar to atoms and coalesce into 3-dimensional bulk-like islands. Medium sized clusters consisting of hundreds of atoms do not coalesce and follow a Stanski-Krastanov growth pattern. At low coverage, an almost perfect monolayer is formed. This is a new finding different from all previous studies on deposited metal clusters. For clusters with several thousands of atoms, the growth pattern again changes. At low coverage, the substrate is dotted with individual clusters, while at high coverage, the surface becomes extremely rough.

Metal Clusters on Semiconductor Surfaces and Application in Catalysis with a Focus on Au and Ru

“…Clusters are smaller than metal nanoparticles and extend down into sub‐nanometer sizes. Scientific interest is motivated by their unique and extraordinary electronic and catalytic properties and their resulting technological potential . While bulk metals feature electron energy band structures, clusters feature discrete electron energies like that of molecules .…”