Kinetics and mechanisms of the reaction of CH with H2O

The rate constant for the CH + H2O reaction has been measured in a fast-flow reactor to be (0.9 ± 0.4) × 10−11 cm3 molecule−1 s−1 at 330 K. The product branching ratio of H atoms probed by resonance fluorescence is determined to be 100%. Quantum chemistry and statistical calculations show that the rate limiting process is the isomerisation of the HCOH2 adduct to H2COH and allow us to propose k = (2.8 ± 1.4) × 10−11(T/300)−1.22 ± 0.07exp(−(12 ± 12)/T) cm3 molecule−1 s−1 in the range 100–700 K for the rate constant of CH + H2O → H + H2CO and H2 + H + CO.