UV absorption spectrum of monochlorodimethyl sulfide (CH3SCH2Cl)

Abstract

Monochlorodimethyl sulfide (CH3SCH2Cl, MCDMS) is a trace gas thought to be formed in the marine environment via the reaction of Cl2 with dimethyl sulfide (DMS, CH3SCH3) with implications for the temporal and spatial production of SO2 and sulfate aerosol formation. In this study, the room temperature UV absorption spectrum of MCDMS in the 200–330 nm wavelength region was measured. The spectrum measured in this work differs significantly in the long-wavelength actinic region, >295 nm, from that reported previously by Copeland et al. (Environ. Sci. Technol., 2014, 48, 1557–1565). On the basis of the present results, the MCDMS first-order tropospheric photolysis rate coefficient is a factor of ∼250 less than reported in Copeland et al. The diurnally averaged MCDMS photolysis lifetime is estimated to be ∼125 days at ground level for Summer mid-latitude conditions over the ocean. UV photolysis is, most likely, a minor gas-phase degradation pathway for MCDMS compared to its OH radical and Cl-atom reactive losses.