Large metal clusters and colloids — Metals in the embryonic state

Abstract

Ligand stabilized transition metal clusters and colloids in the size range of 1–15 nm show size dependent quantization phenomena. Quantum size effects become the more evident the smaller the particle is. Whereas particles >2 nm behave like quantum dots only at low temperatures, the 1.4 nm Au₅₅ cluster follows quantum mechanical rules even at room temperature. First steps to organize clusters and colloids three- (3D), two- (2D) and one- (1D) dimensionally have been performed. 3D arrays are reached by using spacer molecules to link the clusters and to enlarge the distances between them. 2D assemblies are realized in cluster and colloid monolayers on chemically modified surfaces. One-dimensional cluster wires become available by using nanoporous aluminum oxide membranes as templates.