			15min:

THE WEAKLY--BOUND CO₂--ACETYLENE COMPLEX: FUNDAMENTAL AND TORSIONAL COMBINATION BAND IN THE CO₂

₃ REGION.

C. LAUZIN, Laboratoire de Chimie quantique et Photophysique, CP160/09 Faculté des Sciences, Université Libre de Bruxelles (U.L.B.), Ave. Roosevelt, 50 B-1050 Brussels, Belgium; J. NOROOZ OLIAEE, M. REZAEI, N. MOAZZEN-AHMADI, Department of Physics and Astronomy, University of Calgary, Calgary, AB T2N 1N4, Canada.

Infrared spectrum of the weakly-bound CO₂--C₂H₂ complex in the region of the CO₂ ₃ fundamental band ( sim 2349 cm^-1) is observed in a pulsed supersonic slit jet expansion using a tunable diode laser probe. Two bands are observed and analyzed: the fundamental (C--O asymmetric stretch) and a combination involving the intermolecular torsional (out-of-plane bend) vibration. The resulting torsional frequency is 44.385(10) cm^-1. This represents the first observation of an intermolecular frequency for carbon dioxide-acetylene complex. A comparison between the results obtained here and those previously reported for N₂O--C₂H₂ complex is discussed.