Kinetics and mechanisms of the reaction of CH with H2O

Abstract The rate constant for the CH + H 2 O reaction has been measured in a fast-flow reactor to be (0.9 ± 0.4) × 10 −11  cm 3  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 HCOH 2 adduct to H 2 COH and allow us to propose k  = (2.8 ± 1.4) × 10 −11 ( T /300) −1.22 ± 0.07 exp(−(12 ± 12)/ T ) cm 3  molecule −1  s −1 in the range 100–700 K for the rate constant of CH + H 2 O → H + H 2 CO and H 2  + H + CO.