title: Structures of silicon cluster cations in the gas phase.
abstract: We present gas-phase infrared spectra for small silicon cluster cations possessing between 6 and 21 atoms. Infrared multiple photon dissociation (IR-MPD) of these clusters complexed with a xenon atom is employed to obtain their vibrational spectra. These vibrational spectra give for the first time experimental data capable of distinguishing the exact internal structures of the silicon cluster cations. By comparing the experimental spectra with theoretical predictions based on density functional theory (DFT), unambiguous structural assignments for most of the Si(n)(+) clusters in this size range have been made. In particular, for Si(8)(+) an edge-capped pentagonal bypriamid structure, hitherto not considered, was assigned. These structural assignments provide direct experimental evidence for a cluster growth motif starting with a pentagonal bipyramid building block and changing to a trigonal prism for larger clusters.
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany.
authors.forename: Jonathan T
authors.initials: JT
authors.lastname: Lyon
authors.forename: Philipp
authors.initials: P
authors.lastname: Gruene
authors.forename: André
authors.initials: A
authors.lastname: Fielicke
authors.forename: Gerard
authors.initials: G
authors.lastname: Meijer
authors.forename: Ewald
authors.initials: E
authors.lastname: Janssens
authors.forename: Pieterjan
authors.initials: P
authors.lastname: Claes
authors.forename: Peter
authors.initials: P
authors.lastname: Lievens