Guided ion beam studies of the reaction of Nin+ (n=2-16) with D2:: Nickel cluster-deuteride bond energies

The kinetic-energy dependences of the reactions of Ni-n(+) (n=2-16) with D-2 are studied in a guided ion beam tandem mass spectrometer. The products observed are NinD+ for all clusters and NinD2+ for n=5-16. Reactions for formation of NinD+ are observed to exhibit thresholds, whereas cross sections for formation of NinD2+ (n=5-16) exhibit no obvious barriers to reaction. Rate constants of D-2 chemisorption on the cationic clusters are compared with results from previous work on neutral nickel clusters. Ni-n(+)-D bond energies as a function of cluster size are derived from threshold analysis of the kinetic-energy dependence of the endothermic reactions, and are compared to previously determined metal-metal bond energies, D-0(Ni-n(+)-Ni). The bond energies of Ni-n(+)-D generally increase as the cluster size increases, and parallel those for Ni-n(+)-Ni for many clusters. These trends are explained in terms of electronic and geometric structures for the Ni-n(+) clusters. The bond energies of Ni-n(+)-D for larger clusters (ngreater than or equal to11) are found to be close to the value for chemsorption of atomic hydrogen on bulk phase nickel. (C) 2002 American Institute of Physics.