Reactions of N(2 2D) with methane and deuterated methanes

NH radicals and H atoms were identified as products in the reaction of N(2D) with CH4. The absolute yields of NH and H were determined to be 0.3±0.1 and 0.8±0.2, respectively. The rotational state distributions of NH (v″=0) for CH4 and partially deuterated methanes, CHnD4−n (n=1–3), are single modal and peak at N″=13±2, while the vibrational population ratios, NH (v″=1)/NH (v″=0), are 0.6. The rotational energy distribution of ND (v″=0) from CD4 is similar to that for NH (v″=0). The ND (v″=1)/ND (v″=0) ratio is 0.6. Doppler profiles of H and D atoms were measured to evaluate the energy released to the translational mode. It was between 72 and 85 kJ mol−1, suggesting the following H atom production mechanism: N(2D)+CH4→H+CH2NH. The H+CH3N channel is minor. In the reactions with partially deuterated methanes, the isotopic ratios, [H]/[D] and [NH]/[ND], are larger than the stoichiometric ratios in the reactant methanes. These results suggest that C–H bonds are more reactive to N(2D) than C–D bonds, while H atoms are ejected more preferentially than D atoms.