Torsional excitation in the 2CH vibrational overtone of the C2H2-CO2 and C2H2-N2O van der Waals complexes

Clement Lauzin (1) , Keevin Didriche (1) , Tomas Foldes (1) , Michel Herman (1)

1 Service de Chimie Quantique et Photophysique

Infrared spectra of the weakly-bound C2H2-CO2 and C2H2-N2O complexes in the region of the 2CH acetylene overtone band (~1.52 micron) were recorded using CW-cavity ring down spectroscopy in a continuous supersonic expansion. A new, c-type combination band is observed in each case. The rotational analysis of low J, K lines is performed and rotational constants are obtained. The band origins are 40.491(2) and 40.778(2) cm-1 higher in energy than the 2CH excitation bands for C2H2-CO2 and C2H2-N2-1 respectively. The combination band is assigned in each case as involving intermolecular torsional excitation combined to 2CH. The values of the torsional vibrational frequency and of the xCH/torsion anharmonicity constant are briefly discussed.

Mots clés: Physical Sciences

Domaines: Matière Condensée [cond-mat]

Clement Lauzin, Keevin Didriche, Tomas Foldes, Michel Herman. Torsional excitation in the 2CH vibrational overtone of the C2H2-CO2 and C2H2-N2O van der Waals complexes. Molecular Physics, 2011, 109 (17-18), pp.1. ⟨10.1080/00268976.2011.593572⟩. ⟨hal-00730280⟩