Reaction of tungsten anion clusters with molecular and atomic nitrogen

Ultraviolet photoelectron spectra for WnN2 2 (n51 – 8) clusters produced by addition of atomic and molecular nitrogen on W anion clusters are presented. Evidence is provided that molecular chemisorption of N2 is more stable than the dissociative one on tungsten anion clusters consisting of eight atoms or less, which is completely different from the results on tungsten bulk surfaces. A general tendency toward molecular chemisorption for small clusters can be explained by reduced charge transfer from the metallic d-orbitals of cluster in contrast to bulk d-orbitals. Comparative studies on chemisorption of atomic and molecular species of diatomic molecules on nanoclusters are expected to provide important information on size-dependent changes of chemical properties of nanoclusters.