Mechanism of the reaction of CH{sub 3}SO with NO{sub 2} in relation to atmospheric oxidation of dimethyl sulfide: Experimental and theoretical study
CH{sub 3}SO{sub 2} radical decomposition and the mechanism of SO{sub 2} and CH{sub 3} formation in the reaction of CH{sub 3}SO with NO{sub 2} were experimentally investigated in the pressure range 1--612 Torr of He using laser pulsed photolysis/laser-induced fluorescence and discharge flow mass spectrometry/laser-induced fluorescence techniques. The upper limit for the thermal decomposition rate of CH{sub 3}SO{sub 2} in the investigated pressure range has been found to be 100 s{sup {minus}1} at 300 K. High-pressure limit, k{sup infinity} = 2.08 x 10{sup 3} x{sup {minus}1}, and low-pressure limit, k{sup 0} = 2.72 x 10{sup {minus}17} cm{sup 3} molecule{sup {minus}1}s{sup {minus}1}, of the rate coefficient of the CH{sub 3}SO{sub 2}decomposition have been derived from ab initio and RRKM calculations. The CH{sub 3}SO{sub 2} decomposition rate at 760 Torr and 300 K has been estimated to be about 200 s{sup {minus}1} from falloff calculations. Reaction of CH{sub 3}SO with NO{sub 2} has been found to form CH{sub 3} and SO{sub 2} with a yield varying from (0.33 {+-} 0.05) at 13 Torr to (0.18 {+-} 0.03) at 612 Torr of He. The rate constant for the reaction of CH{sub 3}SO with NO{sub 2} has been found to be (1.5 {+-} 0.4) x 10{sup {minus}11} cm{sup 3} molecule{sup {minus}1} s{sup {minus}1} at 300 K, independent of pressure. On the basis of ab initio and RRKM calculations, the experimental results have been interpreted by assuming the reaction of CH{sub 3}SO with NO{sub 2} to form chemically activated CH{sub 3}SO{sub 2}* radical followed by its thermal stabilization or prompt decomposition to CH{sub 3} and SO{sub 2}. The implication of the obtained results for the atmospheric oxidation of dimethyl sulfide is discussed.
- Research Organization:
- Lab. de Combustion et Systems Reactive, Orleans (FR)
- OSTI ID:
- 20017299
- Journal Information:
- Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory, Journal Name: Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory Journal Issue: 5 Vol. 104; ISSN 1089-5639; ISSN JPCAFH
- Country of Publication:
- United States
- Language:
- English
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