Models for statistical decomposition of metal clusters: Vibrational frequency distributions

Abstract

The application of statistical theories to the decomposition kinetics of metal clusters requires the estimation of the vibrational frequency distributions. We adapt elastic theories developed for bulk metals and fine particles to generate a physically reasonable frequency distribution model for small metal clusters. Results obtained from this elastic cluster model compare favorably with previously reported experimental heat capacity data for fine particles. In addition, predictions of the present model are shown to correlate very well with experimentally determined trends in metal cluster cohesive energies. The elastic cluster model is then applied to the statistical unimolecular decay kinetics of metal clusters and compared with results found using earlier theoretical models. The present model predicts slower rates of decomposition in comparison with the other models. These results suggest that the binding energies extracted from experimental photodissociation and collision-induced dissociation measurements may have been slightly overestimated in the past.