Gas phase production and chemistry of transition metal atoms and clusters from polynuclear metal carbonyls

Abstract

The volatility of metal carbonyls and a unique dissociative energy transfer mechanism are exploited to generate gas-phase transition metals at low temperatures. A flowing afterglow of a metastable rare gas produces a flame with metal carbonyls which, when spectrally analysed, is found to consist of metal atom lines. Analysis of the kinetics of this reaction shows it to be bimolecular. Detailed analysis of the spectra shows that the rate of production of a given excited metal state is predicted by a statistical model in which the metal–ligand bonds rupture simultaneously along a radial reaction coordinate. There is little spin differentiation among the metal states produced, and previously unknown transitions from low-lying quintet states of Ni are observed. The possible extensions of this method to metal atom, excited metal atom and metal cluster chemistry are discussed in terms of the electronic excitations produced by metastable atom energy transfer.