Kinetics study of the reaction of iodine monoxide radicals with dimethyl sulfide

Abstract

The temperature and pressure dependence of the rate coefficient for the reaction of iodine monoxide radicals with dimethyl sulfide (DMS), IO + DMS → I + DMSO (1), was studied using laser induced fluorescence (LIF) to monitor the temporal profile of IO following 351 nm photolysis of RI/DMS/NO₂/He (RI = CH₃I/CF₃I) mixtures. The study was performed over the range T = 296–468 K yielding a positive activation energy and k₁ = (9.6 ± 8.8) × 10⁻¹² exp{−(1816 ± 397)/T}. No dependence was observed on total pressure between 5–300 Torr. The rate coefficient at 296 K was determined as (2.0 ± ^0.4_0.6) × 10⁻¹⁴ cm³ molecule⁻¹ s⁻¹, more than an order of magnitude smaller than a recent study but in reasonable agreement with the previous literature.