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The First High-Resolution Analysis of the 10 [mu]m Absorption of Thioformaldehyde

Published

Author(s)

J.- M. Flaud, Walter J. Lafferty, A. Perrin, Y S. Kim, Helmut Beckers

Abstract

The 10 m region of thioformaldehyde (H2CS) has been recorded at high resolution (0.005 cm-1) using a Fourier transform spectrometer. H2CS was produced by low pressure pyrolysis of a gas flow of C3H5SCH3 in Ar at 560oC or CH3SCl at 1150o C which was introduced into a multipass White cell with an optical path length of 32 m. Forty scans were recorded for the range 750-1400 cm-1 at a total pressure of 0.15 mbar. A thorough analysis of the three lowest frequency fundamental bands, ?3, ?4 and ?6, which fall in this region, has been carried out using a Hamiltonian model which takes explicitly into account the numerous resonances affecting the ro-vibrational energy levels; especially the massive A-type Coriolis resonance between the out-of-plane wagging mode,?4 and the in-plane rocking mode, ?6. These two modes are only separated by 0.83 cm-1, and they are thoroughly mixed. From the fittings, the following band centers were derived: ?o (?4) = 990.18213(40) cm-1, ?o (?6) = 991.02021(50) cm-1 and ?o (?3) = 1059.20476 (30) cm-1 where the uncertainties are one standard deviation. In addition a number of relative line intensities were measured permitting the determination of relative values of the first-order transition moments and therefore relative band intensities for all three bands. Finally a comprehensive list of line frequencies and relative intensities has been generated.
Citation
Journal of Chemical Physics
Volume
109

Keywords

High Resolution Infrared Spectrum, line position and intensities, Thiopental, very strong Coriolis resonance

Citation

Flaud, J. , Lafferty, W. , Perrin, A. , Kim, Y. and Beckers, H. (2007), The First High-Resolution Analysis of the 10 [mu]m Absorption of Thioformaldehyde, Journal of Chemical Physics (Accessed April 23, 2024)
Created October 7, 2007, Updated October 12, 2021