Branching ratios in the N+CH3 reaction: Formation of the methylene amidogen (H2CN) radical

The branching ratios for the reaction N+CH3 →Products, have been determined in a discharge-flow system coupled with mass-spectrometric detection of both reactants and products. The major products are H2 CN+H, with about 10% of the reaction proceeding to give HCN+H2 . Experiments carried out on the reaction of N atoms with the deuterated methyl radical showed that the branching ratio for formation of D2 CN+D is about 0.9 and for DCN+D2 formation about 0.1 independent of T from 200 to 363 K. The results are consistent with the energetics and orbital symmetry properties of the reactant and product molecules. Implications for the atmosphere of Titan are discussed.