An experimental and theoretical study of the product distribution of the reaction CH2 ((X)over-tilde B-3(1))+NO

Measurements of the product branching ratios of the reaction CH2 ((X) over tilde B-3(1)) + NO (1) are presented together with calculations of the ther mal rate constant and branching ratios using unimolecular rate theory. The reaction was investigated experimentally at room temperature using FTIR spe ctroscopy. The yields of the main products HCNO and HCN were found to be Ga mma (HCNO) = 0.89 +/- 0.06, Gamma (HCN) = 0.11 +/- 0.06. Other minor produc ts could be rationalized by numerical simulations of the reaction system ta king into account possible consecutive reactions. The potential energy surf ace for the reaction was characterized by quantum chemical calculations usi ng ab initio and density functional methods. The proposed reaction pathways connecting reactants to products were explored by multi-channel unimolecul ar rate theory calculations to determine the CH2 ((X) over tilde) + NO capt ure rate constant and the rate constants for the different product channels as a function of temperature. The calculated capture rate constant of k = 2.3 x 10(13) cm(3) mol(-1) s(-1) is in good agreement with experimental val ues at room temperature. Collisional stabilization of the initial H2CNO rec ombination complex was predicted to be negligible up to pressures of >1 bar . For ambient pressures and temperatures up to 2000 K, HCNO + H were calcul ated as the dominating products, with Gamma (HCNO) approximate to 0.94 in a greement with the experiments. The channel to HCN + OH was calculated with 0.015 less than or equal to Gamma (HCN) less than or equal to 0.05 only sli ghtly below the experimental value.