The title reaction was studied using two different experimental techniques:  laser flash photolysis with resonance fluorescence detection of Cl atoms and continuous photolysis with FTIR detection of end products. Over the temperature range 206−432 K the rate constant for reaction of Cl atoms with CH2ICl is given (to within ±15%) by the Arrhenius expression k 1 = 4.4 × 10-11 exp(195/T) cm3 molecule-1 s-1, which gives k 1 = 8.5 × 10-11 cm3 molecule-1 s-1 at 298 K. Variation of the total pressure of N2 diluent over the range 5−700 Torr at 295 K had no discernible (<10%) effect on the rate of reaction. At 295 K in 100−700 Torr of N2 the reaction proceeds via iodine transfer to give CH2Cl radicals. As part of this work the rate constant k(CH2Cl+O2+M) was measured at 295 K in the presence of 1−800 Torr of N2 diluent. The results were well described by the Troe expression with a broadening factor F c of 0.6 and limiting low- and high-pressure rate constants of k 0 = (1.8 ± 0.1) × 10-30 cm6 molecule-2 s-1 and k ∞ = (3.3 ± 0.3) × 10-12 cm3 molecule -1 s-1. The results are discussed with respect to the available literature for reactions of Cl atoms with halogenated organic compounds and the potential role of the title reaction in atmospheric chemistry.

A laser flash photolysis-resonance fluorescence technique has been employed to investigate the kinetics of reactions of the important stratospheric species bromine nitrate (BrONO 2 ) with ground-state atomic bromine (k 1 ), chlorine (k 2 ), and oxygen (k 3 ) as a function of temperature (224-352 K) and pressure (16-250 Torr of N 2 ). The rate coefficients for all three reactions are found to be independent of pressure and to increase with decreasing temperature. The following Arrhenius expressions adequately describe the observed temperature dependencies (units are 10 -11 cm 3 molecule -1 s -1 ): k 1 ) 1.78 exp(365/T), k 2 ) 6.28 exp(215/T), and k 3 ) 1.91 exp(215/T). The accuracy of reported rate coefficients is estimated to be 15-25% depending on the magnitude of the rate coefficient and on the temperature. Reaction with atomic oxygen is an important stratospheric loss process for bromine nitrate at altitudes above ∼25 km; this reaction should be included in models of stratospheric chemistry if bromine partitioning is to be correctly simulated in the 25-35 km altitude regime.