Fundamental and torsional combination bands of two isomers of the OCS-CO2 complex in the CO2 \u3bd3 region

Spectra of two isomers of the weakly bound complex OCS-CO2 are observed in the region of the CO2 \u3bd3 fundamental vibration ( 3c2349 cm-1), using an infrared tunable diode laser to probe a pulsed supersonic slit-jet expansion. Two bands are measured and analyzed for each isomer, the fundamental asymmetric stretch of the CO 2 component and a combination band involving this fundamental plus the intermolecular out-of-plane torsional mode. For one isomer, the corresponding torsional combination band is also detected in the OCS \u3bd1 stretching region ( 3c2060 cm-1). The resulting torsional frequencies are found to be 18.8 and 15.9 cm-1 for isomers a and b of OCS-CO2, respectively. This may be the first time that such a combination band is observed for a higher-energy isomer of a weakly bound complex. \ua9 2013 American Chemical Society.Peer reviewed: YesNRC publication: Ye