15min:

M. DEHGHANY, J. NOROOZ OLIAEE, 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.

The infrared spectrum of weakly-bound OCS-C₆H₆ is studied in the region of the ₁ fundamental band of OCS ( 2060 cm^-1) using a tunable diode laser spectrometer to probe a pulsed supersonic jet expansion. A very simple band is observed, corresponding to a parallel transition of a symmetric top. It is shifted by -11.1 cm^-1 with respect to the free OCS monomer. The resulting structure has OCS located along the benzene C₆ symmetry axis in an S-bonded configuration with a center of mass separation of 4.42 Å, in good agreement with previous microwave spectra. The isotopomers OCS-¹³C¹²C₅H₆ and OC³⁴S-C₆H₆ are also observed. Similar bands are observed for the OCS-C₆H₆-He and OCS-C₆H₆-Ne trimers, whose structure is obtained by adding an on-axis rare gas atom to the other side of the benzene. However, the analogous band for OCS-C₆H₆-Ar was not detected, raising the possibility that the stable form of this trimer may not have the same symmetrical structure.