Collision-induced dissociation of V<i>n</i>+ (<i>n</i>=2–20) with Xe: Bond energies, dissociation pathways, and structures

Abstract

The kinetic energy dependence of the collision-induced dissociation (CID) of Vn+ (n=2–20) with xenon is studied by using a guided ion beam mass spectrometer. Examination of the general dissociation behavior over a broad collision energy range shows that vanadium cluster ions dissociate primarily by sequential atom loss, although dimer loss is also observed for several clusters, notably V4+. Bond energies of vanadium cluster ions, D(Vn−1+–V), are determined from measurements of the CID thresholds. Bond energies for neutral vanadium clusters are derived by combining these ionic bond energies with literature ionization energies for Vn. The bond energies of cationic and neutral vanadium clusters are very similar and show an even–odd oscillation below n=11 with even-sized clusters being more stable. For larger clusters, prominent stable clusters occur at n=13 and 15. These patterns in stability are found to correlate well with the reactivities of the neutral and cationic clusters, such that stable clusters are the least reactive. Possible electronic and geometric structures consistent with these stability and reactivity patterns are discussed.