title: Onset of carbon-carbon bonding in Ta(5)C(y) (y = 0-6) clusters: a threshold photoionization and density functional theory study.
abstract: We have used photoionization efficiency spectroscopy to determine ionization energies (IEs) of the gas-phase tantalum-carbide clusters Ta(5)C(y) (y = 0-6). The structures of the clusters observed in the experiment are assigned by comparing the experimental IEs with those of candidate isomers, calculated by density functional theory. Two competing geometries of the underlying Ta(5) cluster are found to be present in the assigned Ta(5)C(y) structures; either a "prolate" or "distorted oblate" trigonal bipyramid geometry. The onset of carbon-carbon bonding in the Ta(5)C(y) series is proposed to occur at y = 6, with the structure of Ta(5)C(6) containing two molecular C(2) units.
authors.affiliation: Department of Chemistry, The University of Adelaide, South Australia 5005, Australia.
authors.forename: Viktoras
authors.initials: V
authors.lastname: Dryza
authors.forename: Jason F
authors.initials: JF
authors.lastname: Alvino
authors.forename: Gregory F
authors.initials: GF
authors.lastname: Metha