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 Å and an average slip-angle of 66.3°. Small perturbations are observed in the spectrum of polar (16O13C32S)2, similar to those noted previously in the nonpolar isomer of the same isotopomer.