title: Photodissociation of cobalt and nickel oxide cluster cations.
abstract: Cobalt and nickel oxide cluster cations, Co(x)O(y)(+) and Ni(x)O(y)(+), are produced by laser vaporization of metal rods in a pulsed nozzle cluster source and detected using time-of-flight mass spectrometry. The mass spectra show prominent stoichiometries of x = y for Co(x)O(y)(+) along with x = y and x = y - 1 for Ni(x)O(y)(+). The cluster cations are mass selected and multiphoton photodissociated using the third harmonic (355 nm) of a Nd:YAG laser. Although various channels are observed, photofragmentation exhibits two main forms of dissociation processes in each system. Co(x)O(y)(+) dissociates preferentially through the loss of O(2) and the formation of cobalt oxide clusters with a 1:1 stoichiometry. The Co(4)O(4)(+) cluster seems to be particularly stable. Ni(x)O(y)(+) fragments reveal a similar loss of O(2), although they are found to favor metal-rich fragments with stoichiometries of Ni(x)O(x-1). The Ni(2)O(+) fragment is produced from many parent ions. The patterns in fragmentation here are not nearly as strong as those seen for early or mid-period transition-metal oxides studied previously.
authors.affiliation: Department of Chemistry, University of Georgia, Athens, Georgia 30602-2556, USA.
authors.forename: C J
authors.initials: CJ
authors.lastname: Dibble
authors.forename: S T
authors.initials: ST
authors.lastname: Akin
authors.forename: S
authors.initials: S
authors.lastname: Ard
authors.forename: C P
authors.initials: CP
authors.lastname: Fowler
authors.forename: M A
authors.initials: MA
authors.lastname: Duncan