The rate of reaction of methyl radicals with atomic oxygen

Abstract

The absolute rate constant for the reaction of ground state oxygen atoms with methyl radicals is reported. The methyl radicals were generated by the reaction of oxygen atoms with ethylene in a fast flow reactor, and were detected by a photoionization mass spectrometer. For sufficiently long reacton times, the methyl radicals were observed at their steady state concentration. For shorter reaction times, especially at low oxygen atom concentrations, the methyl radical concentration was less than the steady state value. From the observed approach of the methyl radicals totheir steady state concentration, the rate constant for the reaction, O + CH 3, was determined to be (1.23 ± 0.25) × 10 −10 cm 3 molecule −1 sec −1, corresponding to one reaction in every two gas kinetic collisions.