Imaging a Resonance-Dominant Polyatomic Reaction: F + CH3D → CH3(ν2 = 2) + DF(ν).

The title reaction was studied in a crossed-beam scattering experiment at the collisional energy ( Ec) ranging from 0.46 to 4.53 kcal mol-1. Using a time-sliced velocity-imaging technique, both the pair-correlated integral and differential cross sections were measured. On the basis of the observed structures in state-specific excitation functions and the patterns in the Ec evolution of product angular distributions, we inferred that the title reaction proceeds predominantly via a resonance-mediated pathway, in contrast to the previous findings in the isotopically analogous reactions where the alternative direct abstraction pathway often dominates the reactivity. Despite the complexity of numerous scattering resonances involved in this six-atom reaction, extending our understanding of the isolated resonance in the analogous benchmark F + HD (H2) reaction enables us to propose plausible mechanistic origins for the formation as well as the decay of the complicated overlapped resonances.