Formation, Structure, and Stabilities of Metallocarbohedrenes

Abstract

Time-of-flight mass spectrometric investigations of the formation of metallocarbohedrenes and binary metal metallocarbohedrenes under both direct laser vaporization and laser vaporization/molecular beam conditions were conducted. A wide range of Ti-to-carbon ratios and in other experiments a range of Ti-to-Zr molar ratios were explored. These new studies provide further insight into the formation process of Met-Car clusters and, moreover, serve to eliminate certain suggested formation mechanisms such as one involving the attachment of metal atoms to a preexisting core consisting of a 12-atom carbon cage. There is no evidence in the experiments to suggest that Met-Cars produced via direct laser vaporization exist in a higher energy configuration than those formed in a laser plasma and then subjected to cooling in a molecular beam expansion. Mass spectral distributions of binary metal metallocarbohedrenes produced under widely varying conditions provide evidence that there is one set of equivalent metal sit...