Infrared spectra of the polar isomer of the OCS dimer:: (16O12C32S)2, (16O12C34S)2, and (16O13C32S)2

Infrared spectra of three isotopic forms of the polar OCS dimer are studied in the 2015-2070 cm(-1) region using a tunable laser to probe a pulsed supersonic jet of He + OCS expansion gas. Analysis of the spectra gives accurate band origins as well as rotational parameters for the upper and lower vibrational states. This newly-observed isomer has a slipped near-parallel structure characterized by an intermolecular separation of 3.88 angstrom and an average slip-angle of 66.3 degrees. Small perturbations are observed in the spectrum of polar ((OCS)-O-16-C-13-S-32)(2), similar to those noted previously in the nonpolar isomer of the same isotopomer. (c) 2007 Elsevier B.V. All rights reserved.