Mode Specificity in Reactions of Cl with CH2 Stretch-Excited CH2D2(υ1, υ6 = 1)

We report on a reactive scattering experiment of chlorine atom (Cl) with mode-selected dideutero-methane (CH(2)D(2)) using a pulsed crossed beam approach with a time-sliced velocity-map imaging detection of the methyl radical products. Reactivity with one-quantum excitation of CH(2)D(2) in either CH(2) symmetric (nu(1) = 1) or antisymmetric (nu(6) = 1) stretching mode are contrasted over a wide range of collisional energies, as well as compared to the recently reported reaction dynamics of the ground-state reactants. We found that the vibrational excitation in either stretching mode leads to a nearly identical enhancement factor in total reactivity, which is also comparable to an equivalent amount of additional translational energy. On the other hand, the correlated HCl vibrational distributions from reactions of the two stretch-excited CH(2)D(2) reactants exhibit a distinct mode-specificity. Overall, the observed behaviors bear strong resemblance to the mode-dependent reactivity reported recently for reactions of Cl + CH(4)(nu(3) = 1) and Cl + CHD(3)(nu(1) = 1). The dynamical implications are elucidated and plausible mechanisms proposed.