Kinetics, Energetics and OH Product Yield of the Reaction CH3O + O(3P) → CH3O*2 → Products

The rate constant for the reaction (1) CH3O + O → products at 298 K has been determined using 248 nm laser co‐photolysis of CH3ONO/O3 mixtures for the generation of CH3O radicals and O atoms combined with LTF for time resolved detection of CH3O and product OH. k1 is found to be (2.5±0.7) 10−11 cm3/s with a relative yield of OH of Φ = ‐Δ[OH]/Δ[CH3O] = 0.12+0.08−0.04. The results are shown to be consistent with a primary capture mechanism on an electronically adiabatic surface forming highly vibrationally excited CH3O and followed by rapid subsequent decomposition or isomerization, viz. magnified image . From modelling of the OH yield using RRKM theory the isomerization barrier between CH3O2 and CH2OOH is placed near 160 kJ/mol in good agreement with recent ab initio calculations. As a consequence the CH3 + O2 combustion reaction is predicted to proceed primarily via the low energy CH2O + OH channel, in contrast to most previous suggestions.