Photodissociation dynamics of hydrated Ni2+ clusters:: Ni2+(H2O)n (n=4-7)

Hydrated divalent nickel clusters, Ni2+(H2O)(n) (n = 4-7), have been generated through electrospray ionization and studied with laser photofragment spectroscopy. Clusters containing six and seven water molecules dissociate by loss of either one or two water molecules. in contrast, Ni2+(H2O)(4) dissociates via charge reduction, producing H3O+ + NiOH+(H2O)(2). The modest kinetic energy release in the H3O+ product is in agreement with a salt-bridge dissociation mechanism. Observed dissociation cross-sections indicate that the hexahydrated species is the probable carrier for nickel's aqueous absorption spectrum.