Line positions and strengths of 41 bands including 10 OCS isotopologues in the 3850–4200 cm −1 region

Abstract

The present analysis substantially improves the spectroscopic characterization of near infrared OCS in a window region (3850–4200 cm −1) important for atmospheric studies of Venus. Previous studies in this spectral region cataloged numerous OCS line positions, but accurate line intensities were measured for only three strong bands. In this paper, the corresponding line intensities are obtained for 41 OCS bands, including weak isotopic bands reported for the first time. The 2ν 3 (0002–0000) band is analyzed for 10 OCS isotopologues (adding 16O 13C 34S, 17O 12C 32S, 16O 12C 36S, 18O 12C 34S, and 16O 13C 33S). In addition, observations of 0332–0330 of the main isotope, 16O 12C 32S, provides accurate vibration–rotation parameters for the upper state (and the lower state, 0330 of 16O 12C 32S). Finally, one unidentified band is seen at 3969.3 cm −1; its lower state is clearly the ground state of 16O 12C 32S. The line strengths of these seven previously unanalyzed bands plus 34 other bands of the OCS isotopologues, 16O 12C 32S, 16O 12C 34S, 16O 13C 32S, 16O 12C 33S, and 18O 12C 32S, were least-squares fitted to determine strength parameters, S v and Herman-Wallis coefficients. Finally, the intensities of 17 additional very weak bands were estimated to provide an extensive new database of OCS line parameters to support remote sensing of Venus. The integrated intensity in cm −1/(molecule cm −2) at 296 K is 8.1×10 −19 for the 3800–4200 cm −1 region.