title: Infrared spectra of the OCS-CO(2) complex: Observation of two distinct slipped near-parallel isomers.
abstract: Infrared spectra of OCS-CO(2) complexes are studied in a pulsed supersonic slit-jet expansion using a tunable diode laser probe in the 2060 cm(-1) region of the C-O stretching fundamental of OCS. Two bands are observed and analyzed, corresponding to two distinct isomers of the complex. Isomer a is the known form which has been previously studied in the microwave region. Isomer b is a new form, expected theoretically but first observed here. Structures are determined with the help of isotopic substitution. Both isomers are planar, with slipped near-parallel geometries. In isomer a, the intermolecular (center of mass) separation is 3.55 A and the C atom of the CO(2) is closer to the S atom of the OCS. In isomer b, the C atom of CO(2) slides closer to the O atom of OCS and the center of mass separation increases to 3.99 A. Isomer a is the lowest energy form, but paradoxically isomer b appears to be stronger in our infrared spectra. Predicted pure rotational transition frequencies are given to help in a search for the microwave spectrum of isomer b.
authors.affiliation: Department of Physics and Astronomy, University of Calgary, 2500 University Drive North West, Calgary, Alberta T2N 1N4, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Dehghany
authors.forename: J Norooz
authors.initials: JN
authors.lastname: Oliaee
authors.forename: Mahin
authors.initials: M
authors.lastname: Afshari
authors.forename: N
authors.initials: N
authors.lastname: Moazzen-Ahmadi
authors.forename: A R W
authors.initials: AR
authors.lastname: McKellar