title: Gas-phase infrared spectrum of the protonated water dimer.
abstract: The protonated water dimer is a prototypical system for the study of proton transfer in aqueous solution. We report infrared photodissociation spectra of cooled H+(H2O)2 [and D+(D2O2] ions, measured between 620 and 1900 wave numbers (cm-1). The experiment directly probes the shared proton region of the potential energy surface and reveals three strong bands below 1600 cm-1 and one at 1740 cm-1 (for H5O2+). From a comparison to multidimensional quantum calculations, the three lower energy bands were assigned to stretching and bending fundamentals involving the O...H+...O moiety, and the highest energy band was assigned to a terminal water bend. These results highlight the importance of intermode coupling in shared proton systems.
authors.affiliation: Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, D 14195 Berlin, Germany. asmis@physik.fu-berlin.de
authors.forename: Knut R
authors.initials: KR
authors.lastname: Asmis
authors.forename: Nicholas L
authors.initials: NL
authors.lastname: Pivonka
authors.forename: Gabriele
authors.initials: G
authors.lastname: Santambrogio
authors.forename: Mathias
authors.initials: M
authors.lastname: Brümmer
authors.forename: Cristina
authors.initials: C
authors.lastname: Kaposta
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Neumark
authors.forename: Ludger
authors.initials: L
authors.lastname: Wöste