title: Infrared photodissociation spectroscopy of H(+)(H2O)6·M(m) (M = Ne, Ar, Kr, Xe, H2, N2, and CH4): messenger-dependent balance between H3O(+) and H5O2(+) core isomers.
abstract: Although messenger mediated spectroscopy is a widely-used technique to study gas phase ionic species, effects of messengers themselves are not necessarily clear. In this study, we report infrared photodissociation spectroscopy of H(+)(H(2)O)(6)·M(m) (M = Ne, Ar, Kr, Xe, H(2), N(2), and CH(4)) in the OH stretch region to investigate messenger(M)-dependent cluster structures of the H(+)(H(2)O)(6) moiety. The H(+)(H(2)O)(6), the protonated water hexamer, is the smallest system in which both the H(3)O(+) (Eigen) and H(5)O(2)(+) (Zundel) hydrated proton motifs coexist. All the spectra show narrower band widths reflecting reduced internal energy (lower vibrational temperature) in comparison with bare H(+)(H(2)O)(6). The Xe-, CH(4)-, and N(2)-mediated spectra show additional band features due to the relatively strong perturbation of the messenger. The observed band patterns in the Ar-, Kr-, Xe-, N(2)-, and CH(4)-mediated spectra are attributed mainly to the "Zundel" type isomer, which is more stable. On the other hand, the Ne- and H(2)-mediated spectra are accounted for by a mixture of the "Eigen" and "Zundel" types, like that of bare H(+)(H(2)O)(6). These results suggest that a messenger sometimes imposes unexpected isomer-selectivity even though it has been thought to be inert. Plausible origins of the isomer-selectivity are also discussed.
authors.affiliation: Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
authors.forename: Kenta
authors.initials: K
authors.lastname: Mizuse
authors.forename: Asuka
authors.initials: A
authors.lastname: Fujii
mesh_terms: D001128:Argon / Q000737:chemistry; D006859:Hydrogen / Q000737:chemistry*; D006878:Hydroxides / Q000737:chemistry; D007536:Isomerism; D007726:Krypton / Q000737:chemistry; D008697:Methane / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D009356:Neon / Q000737:chemistry; D009584:Nitrogen / Q000737:chemistry*; D005741:Noble Gases / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D014867:Water / Q000737:chemistry*; D014978:Xenon / Q000737:chemistry
chemical_list: D006878:Hydroxides; D005741:Noble Gases; D014867:Water; D014978:Xenon; D009356:Neon; D007726:Krypton; D001128:Argon; D006859:Hydrogen; C031356:hydroxide ion; D009584:Nitrogen; D008697:Methane