PRODUCT CN ROTATIONAL DISTRIBUTIONS FROM THE H+HCN REACTION

Quantum scattering calculations are reported of the CN rotational distributions obtained in the reaction H + HCN --> H-2 + CN The rotating bond approximation (RBA) is used with a potential energy surface based on ab initio data. The product rotational distributions of CN are found to be relatively insensitive to the degree of excitation of the CH stretching vibration and the collision energy. They are very sensitive, however, to the degree of initial excitation in the HCN bending mode and show the structures predicted by a simple Franck-Condon projection of the HCN bending mode onto the product CN rotation. Good agreement with experiment is obtained for the CN rotational distributions calculated for the reaction with four quanta in the initial CH stretching vibration of HCN. The importance of the CN rotational distributions for providing information on the potential energy surfaces for the X + HCN --> HX + CN reactions (X = H, O, and Cl) is also discussed.