Direct Measurement of the Reaction CH3 + OH at Ambient Temperature in the Pressure Range 0.3 - 6.2 mbar

Article abstract of DOI:10.1021/j100192a034

The falloff behavior of the CH3 + OH recombination reaction CH3 + OH -> CH3OH (1a) has been quantitatively investigated for the first time.Methyl decay profiles were measured in a flow reactor at 300 K and in a pressure range between 0.3 and 6.2 mbar.The experimental conditions were such that a possible channel to 1CH2 + H2O did not contribute strongly to the CH3 profiles.Rate coefficients were extracted from the data by comparison of the experimental profiles with compouter simulations.The results are in accord with the limiting rate coefficient suggested by Hochanadel et al., k_1a(298 K) = 9.3 * 10^-11 cm³ molecule^-1 s^-1.The experimental falloff curve is described by use of this value for K, together with an interpolation formula given by Troe, from which an approximate value for the low-pressure limit K⁰_1a = (2.5 +/- 1.0) * 10^-27 cm⁶ molecule^-2 s^-1 has been derived (bath gas helium).For a quantitative assessment of the possible channel to 1CH2 + H2O, reaction 1d measurements of H2O were carried out, yielding an estimated upper limit for the rate coefficient of K_1d(300 K) -12 cm³ molecule^-1 s^-1.