Infrared observation of OC-C2H2, OC-(C2H2)2 and their isotopologues |
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| Authors: | A J Barclay A Mohandesi K H Michaelian A R W McKellar |
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| Institution: | 1. Department of Physics and Astronomy, University of Calgary , Calgary, Canada;2. Natural Resources Canada, CanmetENERGY , Devon, Canada;3. National Research Council of Canada , Ottawa, Canada |
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| Abstract: | ABSTRACTThe fundamental band for the OC-C2H2 dimer and two combination bands involving the intermolecular bending modes ν9 and ν8 in the carbon monoxide CO stretch region are re-examined. Spectra are obtained using a pulsed supersonic slit jet expansion probed with a mode-hop free tuneable infrared quantum cascade laser. Analogous bands for OC-C2D2 and the fundamental for OC–DCCH as an impurity are also observed and analysed. A much weaker band in the same spectral region is assigned to a new mixed trimer, CO-(C2H2)2. The trimer band is composed uniquely of a-type transitions, establishing that the CO monomer is nearly aligned with the a-inertial axis. The observed rotational constants agree well with ab initio calculations and a small inertial defect value indicates that the trimer is planar. The structure is a compromise between the T-shaped structure of free acetylene dimer and the linear geometry of free OC-C2H2. A similar band for the fully deuterated isotopologue CO-(C2D2)2 confirms our assignment. |
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| Keywords: | Molecular cluster infrared quantum cascade laser high resolution intermolecular modes |
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