The rate constants of the reaction between hydroxyl radical (OH-) and dimethyl sulfide (DMS) were investigated by using the relative methods in air, N2, and 02. Strong influences of ground state oxygen O(3p) on DMS consumption were found by the photolysis of HONO and CH3ONO as OH. sources, and the rate constants obtained in these systems varied significantly. The rate constants of the reaction between DMS and OH- (generated by photolysis of H2 O2) at room temperature were 8.56 × 10^-12, 11.31× 10^-12, and 4.50× 10^-12 cm3/(molecule.s), in air, O2, and N2, respectively. The temperature dependence of the rate constants for OH- with DMS over the temperature range of 287-338 K was also investigated in nitrogen and air, and the Arrhenius expression was obtained as follows: kaire=(7.24±0.28)× 10^-13exp[(770.7±E97.2)/T], kN2 =(3.40±0.15) × 10^-11 exp[-- (590.3±165.9)/T].
The rate constant for the reaction of OH radicals and hydrogen sulfide (H2S) was studied in different bath gases (including N2, air, O2 and He) by using relative technique at 298 K. The small difference of the measured rate constants between N2 and those with the presence of O2 suggested possible influence of HS self reaction. Further experiments with NOx presence for scavenging HS demonstrated this assumption. The rate constant of (5.48±0.12) ×10-12 cm3 molecule-1 s-1 obtained with 4.09 ×10-4 mol m3 NO presence may be accurate for estimating the atmospheric lifetime of H2S. The results provided circumstantial evidence that the rapid reaction of HS with N2O is suspected.
Absolute rate constants for the reaction of ozone with dimethyl sulfide (DMS) were measured in a 200-L Teflon chamber over the temperature range of 283-353 K. Measurements were carried out using DMS in large excess over ozone of 10 to 1 or greater. Over the indicated temperature range, the data could be fit to the simple Arrhenius expression as kDMS = (9.96 ± 3.61) × 10^-11 exp (-(7309.7 ± 1098.2)/T) cm^3/(molecule.s). A compared investigation of the reaction between ozone and ethene had a kC2H4 value of (1.35 ± 0.11) × 10^-18 cm^3/(molecule.s) at room temperature.