Enlarging the reactive cone of acceptance by exciting the C–H bond in the O(3P) + CHD3 reaction

The effects of the CH stretching vibration of methane on the O(3P) + CHD3 reaction are elucidated in a crossed-beam imaging experiment. For the H-atom abstraction channel, the ground state reaction leads mainly to the vibrational ground states of products, OH(v = 0) + CD3(v = 0). When the reactant CHD3 is prepared with one-quantum excitation of CH stretching vibration (v1 = 1), more than 90% of OH coproducts that formed concomitantly with the CD3(v = 0) product are in v = 1. Significant vibrational enhancement in the reaction rate is observed, and the product angular distribution shifts from a backward-dominance in O(3P) + CHD3(v = 0) to a sideways-peaking upon CH stretching excitation. As to the D-atom abstraction channel, the C–H bond excitation, despite being conserved in the CHD2 product, unexpectedly hinders the overall reactivity of the unexcited C–D bond. We interpret the experimental findings as the result of enlarging the reactive cone of acceptance in abstracting the H atom at the expense of the cone for the D-atom transfer channel.