Rate constant for the reaction of the CFCl 2 radical with oxygen in the pressure range 0.2–12 Torr at 298 K

Abstract

The rate constant for the reaction of CFCl 2 with oxygen is measured in the pressure range 0.2–12 Torr using pulsed-laser photolysis and time-resolved mass spectrometry. CFCl 2 radicals are generated by photolysis of CFCl 3 at 193 nm. The reaction kinetics are recorded by monitoring the build-up of the CFCl 2O 2 radical concentration. The reaction is in its fall-off region, and the parameters of the relation for the treatment of the fall-off are for M = N 2: k(0) = (5.0 ± 0.8) × 10 −30 cm 6 molecule −2 s −1. k(∞) = (6.0 ± 1.0) × 10 −12 cm 3 molecule −1 s −1. This value of k(∞) is consistent with results obtained at low pressure taking F c = 0.6, but the uncertainty in the high-pressure limit is much higher. The results are compared to measurements performed with CH 3 and CF 3. Estimates of the relative third-body efficiencies of He and N 2 are given for CFCl 2 and CF 3.