Velocity map imaging study of the reaction dynamics of the H + CH4 → H2 + CH3 reaction: the isotope effects.

Following our previous study on the H + CD4 → HD + CD3 reaction [ Proc. Natl. Acad. Sci. U.S.A. 2010 , 107 , 12782 ], the reaction of H + CH4 → H2 + CH3 at collision energies ranging from 0.72 to 1.99 eV is studied using crossed-beam and time-sliced velocity map ion imaging techniques. The product angular and translational energy distributions at four different collision energies were derived from the measured images. The excitation function was also measured from these images together with a careful calibration of the H atom beam intensities at different collision energies. All of these results are compared with those of the H + CD4 reaction to investigate the isotope effects. The isotope effects are all observed in the product angular distributions, the translational energy distributions, and the excitation function and further confirm the reaction mechanism proposed in the previous study on the H + CD4 reaction.