			15min:

INFRARED SPECTROSCOPY OF TWO ISOMERS OF THE OCS-CS₂ COMPLEX.

J. N. OLIAEE, M. DEHGHANY, MAHIN AFSHARI, N. MOAZZEN-AHMADI, Department of Physics and Astronomy, University of Calgary, 2500 University Dr., N.W., Calgary, Alberta T2N 1N4, Canada; A. R. W. MCKELLAR, Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, Ontario, K1A 0R6, Canada.

A second isomer of OCS-CS₂ complex, with a nonplanar cross-shaped structure, has been studied for the first time by analysing an infrared band in the region of the OCS stretching vibration (2062 cm^-1). This isomer has C_s symmetry and the observed band consists of purely c-type rotational transitions. The ground state rotational parameters are found to be A=0.07306 cm^-1, B=0.03325 cm^-1 and C=0.02879 cm^-1, in good agreement with a previous semi-empirical calculation. In addition, a hybrid band with a- and b-type rotational transitions has been assigned to be due to the known planar form of OCS-CS₂, as previously studied by microwave spectroscopy.^ riptsizea The spectra were recorded using a rapid-scan tunable diode laser spectrometer to probe a pulsed supersonic jet expansion. Calculations indicate that the planar isomer of OCS-CS₂ is the lowest in energy, in contrast to CO₂-CS₂ where the crossed form is believed to be the lowest.