title: Vibrational signatures of hydrogen bonding in the protonated ammonia clusters NH4(+)(NH3)(1-4).
abstract: The gas phase vibrational spectroscopy of the protonated ammonia dimer N(2)H(7)(+), a prototypical system for strong hydrogen bonding, is studied in the spectral region from 330 to 1650 cm(-1) by combining infrared multiple photon dissociation and multidimensional quantum mechanical simulations. The fundamental transition of the antisymmetric proton stretching vibration is observed at 374 cm(-1) and assigned on the basis of a six-dimensional model Hamiltonian, which predicts this transition at 471 cm(-1). Photodissociation spectra of the larger protonated ammonia clusters NH(4)(+)(NH(3))(n) with n=2-4 are also reported for the range from 1050 to 1575 cm(-1). The main absorption features can be assigned within the harmonic approximation, supporting earlier evidence that hydrogen bonding in these clusters is considerably weaker than for n=1.
authors.affiliation: Institut für Chemie und Biochemie, Freie Universität Berlin, Takustr. 3, D-14195 Berlin, Germany.
authors.forename: Y
authors.initials: Y
authors.lastname: Yang
authors.forename: O
authors.initials: O
authors.lastname: Kühn
authors.forename: G
authors.initials: G
authors.lastname: Santambrogio
authors.forename: D J
authors.initials: DJ
authors.lastname: Goebbert
authors.forename: K R
authors.initials: KR
authors.lastname: Asmis
mesh_terms: D000641:Ammonia / Q000737:chemistry*; D006860:Hydrogen Bonding; D011522:Protons; D013055:Spectrophotometry, Infrared; D013816:Thermodynamics; D014732:Vibration
chemical_list: D011522:Protons; D000641:Ammonia