Abstract book - Prof. Per Jensen, Ph.D. - Bergische Universität ...

136 Poster session, H23Spectroscopy of (C 2 D 2 ) 2 , (C 2 D 2 ) 3 , C 2 D 2 -He, and C 2 D 2 -NeMojtaba Rezaei 1 , J. Norooz Oliaee 1 , N. Moazzen-Ahmadi 1 , A.R.W. McKellar 21 Department of Physics and Astronomy, University of Calgary, Calgary, AB T2N 1N4,Canada, ahmadi@phys.ucalagary.ca; 2 National Research Council of Canada, Ottawa,ON K1A 0R6, Canada, robert.mckellar@nrc-cnrc.gc.caSpectra of acetylene-containing complexes are studied in the C 2D 2 ν 3 fundamental bandregion (≈2440 cm -1 ) using a tunable infrared diode laser to probe a pulsed supersonicslit jet expansion. Extending our previous work 1 on (C 2D 2) 2, four new perpendicularsubbands are observed, enabling the first direct determination of the A rotationalconstant for an acetylene dimer. This parameter turns out to be significantly larger thanthe previous indirect value based on microwave spectra. 2 The parallel band of (C 2D 2) 2 islocated, but found to be highly perturbed. The trimers (C 2D 2) 3, (C 2D 2) 2 – C 2H 2, andC 2 D 2 – (C 2 H 2 ) 2 are observed spectroscopically for the first time (see Fig. 1).Rezaei M.Norooz OliaeeMoazzen-Ahmadi N.McKellar A.R.W.observedsimulatedsumC 2 D 2 - (C 2 H 2 ) 2(C 2 D 2 ) 2 - C 2 H 2(C 2 D 2 ) 32423.5 2424.0 2424.5 2425.0Wavenumber / cm -1Fig. 1: Observed and simulated (using PGopher) spectra of acetylene trimers obtainedusing a mixture of C 2D 2 and C 2H 2.Rotational assignments of the He – C 2D 2 complex are made with the help of an ab initiointermolecular potential 3 and fitted using a simple Coriolis model. There are noprevious published experimental spectra for helium – acetylene, probably because thiscomplex is close to the free rotor limit, causing most transitions to pile up in a narrowspectral region. Ne – C 2 D 2 also poses assignment challenges, but Ar – C 2 D 2 behavesmore or less like a conventional asymmetric rotor molecule.References[1] C. Lauzin, N. Moazzen-Ahmadi, and A.R.W. McKellar, J. Mol. Spectrosc. 269, 124,2011.[2] K. Matsumura, F.J. Lovas, and R.D. Suenram, J. Mol. Spectrosc. 150, 576, 1991.[3] R. Munteanu and B. Fernández, J. Chem. Phys. 123, 014309, 2005.