Kinetics into the steady state. I. study of the reaction of oxygen atoms with methyl radicals

Abstract
The exponential relaxation of CH3, produced by the reaction O + C2H4 → CH3 + HCO, to its steady‐state concentration was quantitatively monitored after the reactants were mixed. The relaxation profiles yield the rate constant of the reaction O + CH3 → H2CO + H equal to (1.85 ± 0.28) × 10‐10 cm3/molecule‐sec at 300°K. Ancillary experiments yielded values for the rate constant for the reaction of O atoms with C2H4 at 300°K, the average of which is 7.7 × 10‐12 cm3/molecule‐sec. The experimental technique, which employs a fast‐flow reactor coupled to a photoionization mass spectrometer, is described in detail and its potential discussed.