title: Structure determination of neutral MgO clusters--hexagonal nanotubes and cages.
abstract: Structural information for neutral magnesium oxide clusters has been obtained by a comparison of their experimental vibrational spectra with predictions from theory. (MgO)(n) clusters with n = 3-16 have been studied in the gas phase with a tunable IR-UV two-color ionization scheme and size-selective infrared spectra have been measured. These IR spectra are compared to the calculated spectra of the global minimum structures predicted by a hybrid ab initio genetic algorithm. The comparison shows clear evidence that clusters of the composition (MgO)(3k) (k = 1-5) form hexagonal tubes, which confirm previous theoretical predictions. For the intermediate sizes (n≠ 3k) cage-like structures containing hexagonal (MgO)(3) rings are identified. Except for the cubic (MgO)(4) no evidence for bulk like structures is found.
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany.
authors.forename: Marko
authors.initials: M
authors.lastname: Haertelt
authors.forename: André
authors.initials: A
authors.lastname: Fielicke
authors.forename: Gerard
authors.initials: G
authors.lastname: Meijer
authors.forename: Karolina
authors.initials: K
authors.lastname: Kwapien
authors.forename: Marek
authors.initials: M
authors.lastname: Sierka
authors.forename: Joachim
authors.initials: J
authors.lastname: Sauer