Absolute rate constant for the reaction of O(3P) with CH3SSCH3 from 270 to 329 K

Abstract

Rate constants for the oxidation reactions of organic sulfur compounds have become increasingly important due to the potential role of these compounds in the formation of tropospheric and stratospheric sulfate aerosols. The present study deals with the reaction of the ground state oxygen atom with dimethyl disulfide (DMDS). The discharge fast flow–resonance fluorescence technique was used to monitor the decay of O(3P) concentration in the presence of excess CH3SSCH3 under pseudo-first-order conditions. Over a temperature range from 270 to 329 K, and a pressure range from 0.52 to 2.60 Torr, no variation of the rate constant with temperature and pressure was observed. The results are best represented by the temperature and pressure independent value of (2.12±0.22)×10−10 cm3 molecule−1 s−1, which is about one-half the theoretical collision frequency. The zero activation energy for this reaction is discussed in terms of the temperature dependence of other sulfur compound–oxygen atom reactions reported in the literature.