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MO: Molekülphysik
MO 15: Molecular Clusters II
MO 15.9: Talk
Monday, March 13, 2006, 18:30–18:45, H10
IR and UV spectra of the gas-phase benzene dimer — •Undine Erlekam, Marcin Frankowski, Gert von Helden, and Gerard Meijer — Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin
The benzene dimer is a simple prototype system to get insight into dispersive interactions between aromatic molecules.
We investigate the benzene dimer via two-colour Resonance Enhanced Multi Photon Ionization (REMPI) and mass-selective Infrared (IR) ion dip spectroscopy in the C-H-stretch region. Benzene clusters are formed and internally cooled in a supersonic jet expansion. A few ns before UV excitation and ionization, the molecular beam is interrogated by a tunable IR laser. If the IR photons are resonant with a vibration in the complex, population is transferred into a vibrationally excited state, leading to a reduction of the ion signal. By recording the ion yield while tuning the IR wavelength, the IR spectrum is obtained.
UV and IR spectra of (C6H6), (C6H6)2 and (C6H6)(C6D6) will be presented. (C6H6)(C6D6) forms two isomers having different UV excitation as well as IR spectra. Surprisingly, the relative population of the two different isomers depends extremely on experimental conditions.