Experimental and RRKM Modeling Study of the CH3+H and CH3+D Reactions

Article abstract of DOI:10.1021/j100347a037

Rate coefficients for the reactions CH3+H and CH3+D are presented over the temperature ranges 300* to generate CH2D+H is much faster than that to regenerate CH3+D under all conditions studied; in consequence the measured rate coefficient corresponds, in effect, to the high-pressure limit, k^infinite₁(D).Fits to the CH3+H falloff data show that the high-pressure limit, k^infinite₁(H), at 300 K exceeds that predicted from k^infinite₁(D) by at least a factor of 2.This conclusion is confirmed by detailed master equation calculations that incorporate microcanonical dissociation rate coefficients calculated on the basis of a variational RRKM procedure.Parameters are provided that give a satisfactory representation of the CH3+H rate data, over the experimental pressure and tempereture ranges, with a temperature-independence value of k^infinite₁(H) of 4.7E-10 cm³ molecule^-1s^-1 with uncertainties of Δlog k^infinite₁(H) ca. +0.2 to -0.1 at 300 K rising to ca. +/-0.4 at 600 K.