Line strength measurements of carbonyl sulfide (16O12C32S) in the 2v3, v1+2v2+v3, and 4v2+v3 bands

To support planetary studies of the Venus atmosphere, we measured line strengths of the 2v3, v1+2v2+v3, and 4v2+v3 bands of the primary isotopologue of carbonyl sulfide (16O12C32S), whose band centers are located at 4101.387, 3937.427, and 4141.212 cm-1, respectively. For this, infrared absorption spectra in normal carbonyl sulfide (OCS) sample gas were recorded at an unapodized resolution of 0.0033 cm-1 at ambient room temperatures using a Bruker Fourier transform spectrometer (FTS) at the Jet Propulsion Laboratory. The FTS instrumental line shape (ILS) function was investigated, which revealed no significant instrumental line broadening or distortions. Various custom-made short cells and a multi-pass White cell were employed to achieve optical densities sufficient to observe the strong 2v3 and the weaker bands in the region. Gas sample impurities and the isotopic abundances were determined from mass spectrum analysis. Line strengths were retrieved spectrum by spectrum using a non-linear curve fitting algorithm adopting a standard Voigt line profile, from which Herman-Wallis factors were derived for the three bands. The band strengths of 2v3, v1+2v2+v3, and 4v2+v3 of 16O12C32S (normalized at 100% of isotopologue) are observed to be 6.315(13)x10-19, 1.570(2)x10-20, and 7.949(20)x10-21 cm-1/molecule cm-2, respectively, at 296 K. These results are compared with earlier measurements and the HITRAN 2004 database.