Ft-Ir Product Study On The Oh Radical Initiated Oxidation Of Dimethyl Sulfide: Temperature And O2 Partial Pressure Dependence
The products of the OH radical initiated oxidation of dimethyl sulfide (DMS) have been investigated under NOx-free conditions using the photolysis of H2O2 as the OH radical source and FT-IR spectroscopy to monitor reactants and products. The experiments were performed at five different temperatures (260, 270, 280, 290 and 298 K), at three different O2 partial pressure (̃0, 205 and 500 mbar) and at a total pressure of 1,000 mbar diluent gas (N2, synthetic air or N2/O2 mixture). The major sulfur-containing products were dimethyl sulfoxide (DMSO) and sulfur dioxide (SOM2). As minor sulfur-containing products dimethyl sulfone (DMSO2), methyl thiol formate (MTF) and carbonyl sulfide (OCS) have been identified; the formation of trace amounts of methane sulfonic acid (MSA) were also observed. The variation of the product yields with temperature and O2 partial pressure is consistent with the occurrence of both addition and abstraction channels in the OH radical initiated oxidation of DMS. The molar formation yields of DMSO support that a major fraction of the DMS-OH adduct formed in the addition channel reacts with O2 to form DMSO.
KeywordsDimethyl sulfide hydroxyl radical marine atmosphere photooxidation products
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