Photofragmentation of Mass-Selected Main Group Element Cations

Abstract

Mass-selected photofragmentation of cluster cations of C, Bi, and Sb was studied. In the case of C a detailed study led to dissocn. branching ratios, thresholds, and cross sections. The dominant feature seen in the dissocn. pathway for Cn+ is the loss of a neutral C3 for clusters in the n = 6-20 range. For photodissocn. thresholds and cross sections, the most interesting feature is the change in these properties as a function of cluster size. Wavelength independence of the dissocn. products coupled with collisional dissocn. data suggests that the mechanism is most likely a statistical dissocn. (i.e. unimol. decay). For Bi and Sb preliminary results yielded dissocn. branching ratios. In all cases the primary dissocn. pathway is the loss of a mol. species unlike the single atom loss for transition metal clusters. Due to the fact that the photodissocn. pathways to favor the prodn. of a stable product mols. (i.e. stable cations or neutrals), the same statistical dissocn. mechanism as proposed for C seems likely to occur in Bi and Sb.