Photodissociation of gaseous CH{sub 3}COSH at 248 nm by time-resolved Fourier-transform infrared emission spectroscopy: Observation of three dissociation channels

Journal Article · Mon Jan 07 04:00:00 EST 2013 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.4768872· OSTI ID:22099160

Hu, En-Lan; Tsai, Po-Yu; Fan, He; Lin, King-Chuen ^[1]

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1. Department of Chemistry, National Taiwan University, Taipei 106, Taiwan (China) and Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan (China)

Upon one-photon excitation at 248 nm, gaseous CH{sub 3}C(O)SH is dissociated following three pathways with the products of (1) OCS + CH{sub 4}, (2) CH{sub 3}SH + CO, and (3) CH{sub 2}CO + H{sub 2}S that are detected using time-resolved Fourier-transform infrared emission spectroscopy. The excited state {sup 1}(n{sub O}, {pi}{sup *}{sub CO}) has a radiative lifetime of 249 {+-} 11 ns long enough to allow for Ar collisions that induce internal conversion and enhance the fragment yields. The rate constant of collision-induced internal conversion is estimated to be 1.1 Multiplication-Sign 10{sup -10} cm{sup 3} molecule{sup -1} s{sup -1}. Among the primary dissociation products, a fraction of the CH{sub 2}CO moiety may undergo further decomposition to CH{sub 2}+ CO, of which CH{sub 2} is confirmed by reaction with O{sub 2} producing CO{sub 2}, CO, OH, and H{sub 2}CO. Such a secondary decomposition was not observed previously in the Ar matrix-isolated experiments. The high-resolution spectra of CO are analyzed to determine the ro-vibrational energy deposition of 8.7 {+-} 0.7 kcal/mol, while the remaining primary products with smaller rotational constants are recognized but cannot be spectrally resolved. The CO fragment detected is mainly ascribed to the primary production. A prior distribution method is applied to predict the vibrational distribution of CO that is consistent with the experimental findings.

• OSTI ID: 22099160
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 1 Vol. 138; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
74 ATOMIC AND MOLECULAR PHYSICS
ATOM-MOLECULE COLLISIONS
CARBON DIOXIDE
CARBON MONOXIDE
DISSOCIATION
DISTRIBUTION
EMISSION SPECTROSCOPY
EXCITATION
FOURIER TRANSFORMATION
HYDROGEN COMPOUNDS
INFRARED SPECTRA
INTERNAL CONVERSION
METHANE
ORGANIC SULFUR COMPOUNDS
PHOTOLYSIS
REACTION KINETICS
TIME RESOLUTION
VIBRATIONAL STATES