GUIDED ION-BEAM STUDIES OF THE REACTIONS OF V-N(-17) WITH O-2 - BOND-ENERGIES AND DISSOCIATION PATHWAYS() (N=2)

The kinetic energy dependence of the reactions of V-n(+) (n = 2-17) wi th oxygen is studied using a guided ion beam mass spectrometer. In all but the smallest clusters, the primary reaction process at low energi es is the formation of a vanadium cluster dioxide ion which then loses one or two vanadium atoms or a vanadium oxide diatom (VO). Vanadium a tom loss is the preferred reaction pathway for large clusters (n great er than or equal to 5), whereas loss of VO is more favorable for the s mallest reactant clusters (n less than or equal to 4). As the collisio n energy is increased, these primary products dissociate further by lo ss of additional vanadium atoms. Bond dissociation energies of the van adium cluster oxides are determined by analysis of the kinetic energy dependence of several different products. The effect of oxygen atoms o n the stabilities of vanadium cluster ions is discussed and compared w ith bulk phase thermochemistry. (C) 1998 American Institute of Physics .