A temperature‐dependent kinetics study of the reaction of O( 3 P J ) with (CH 3 ) 2 SO

A laser flash photolysis–resonance fluorescence technique has been employed to investigate the kinetics of the reaction of ground state oxygen atoms, O( 3 P J ), with (CH 3 ) 2 SO (dimethylsulfoxide) as a function of temperature (266–383 K) and pressure (20–100 Torr N 2 ). The rate coefficient ( k R1 ) for the O( 3 P J ) + (CH 3 ) 2 SO reaction is found to be independent of pressure and to increase with decreasing temperature. The following Arrhenius expression adequately describes the observed temperature dependence: k R1 (T) = (1.68 ± 0.76) × 10 −12 exp[(445 ± 141)/T] cm 3 molecule −1 s −1 , where the uncertainties in Arrhenius parameters are 2σ and represent precision only. The absolute accuracy of each measured rate coefficient is estimated to be ±30%, and is limited predominantly by the uncertainties in measured (CH 3 ) 2 SO concentrations. The observed temperature and pressure dependencies suggest that, as in the case of O( 3 P J ) reactions with CH 3 SH and (CH 3 ) 2 S, reaction occurs by addition of O( 3 P J ) to the sulfur atom followed by rapid fragmentation of the energized adduct to products. The O( 3 P J ) + (CH 3 ) 2 SO reaction is fast enough so that it could be a useful laboratory source of the CH 3 SO 2 radical if this species is produced in significant yield. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 156–161, 2002; DOI 10.1002/kin.10040