Reaction dynamics and isotope effects in the D + CD4 → D2 + CD3 reaction

The H + CH4 reaction and its isotopic variant reactions serve as a benchmark reaction system to understand the dynamics of polyatomic reactions. In this paper, we report a vibrationally state-resolved crossed molecular beam study on the D + CD4 → D2 + CD3 reaction using the time-sliced velocity map ion imaging method. Pronounced collision energy dependence is found in product kinetic energy distributions and angular distributions. At 0.67 eV, CD3 products are dominantly distributed in the backward direction with D2 products in the vibrational ground state. As collision energy increases, the angular distributions of CD3 products shift from the backward direction to the sideways and forward directions, and vibrational excited D2 appears and intensifies. By comparing our result of the D + CD4 → D2 + CD3 reaction with previous studies on the D + CH4 → HD + CH3 and H + CD4 → HD + CD3 reactions, isotope effects have been discussed. The product kinetic energy and angular distributions vary significantly among the three isotopic variant reactions.