title: Geometry of the magic number H(+)(H2O)21 water cluster by proxy.
abstract: Abundance mass spectra, obtained upon carefully electrospraying solutions of tert-butanol (TB) in water into a mass spectrometer, display a systematic series of peaks due to mixed H(+)(TB)m(H2O)n clusters. Clusters with m + n = 21 have higher abundance (magic number peaks) than their neighbours when m ≤ 9, while for m > 9 they have lower abundance. This indicates that the mixed TB-H2O clusters retain a core hydrogen bonded network analogous to that in the famous all-water H(+)(H2O)21 cluster up to the limit m = 9. The limiting value corresponds to the number of dangling O-H groups pointing out from the surface of the degenerated pentagonal dodecahedral, considered to be the lowest energy form of H(+)(H2O)21; the experimental findings therefore support this geometry. The experimental findings are supported by ab initio quantum chemical calculations to provide a consistent framework for the interpretation of these kinds of experiments.
authors.affiliation: Mass Spectrometry Laboratory and Centre for Theoretical and Computational Chemistry (CTCC), Department of Chemistry, University of Oslo, P. O. B. 1033 Blindern, NO-0315 Oslo, Norway. Mauritz.ryding@kjemi.uio.no einar.uggerud@kjemi.uio.no.
authors.forename: Mauritz Johan
authors.initials: MJ
authors.lastname: Ryding
authors.forename: Róbert
authors.initials: R
authors.lastname: Izsák
authors.forename: Patrick
authors.initials: P
authors.lastname: Merlot
authors.forename: Simen
authors.initials: S
authors.lastname: Reine
authors.forename: Trygve
authors.initials: T
authors.lastname: Helgaker
authors.forename: Einar
authors.initials: E
authors.lastname: Uggerud