STRUCTURES IN THE ENERGY-DEPENDENCE OF THE RATE-CONSTANT FOR KETENE ISOMERIZATION

The isomerization of highly vibrationally excited and rotationally cold ketene has been investigated by monitoring the (CO)-C-12 and (CO)-C-13 dissociation products following laser excitation of jet-cooled (CH2)-C-12 (CO)-13, (CH2)-C-13 (CO)-C-12, and (CD2)-C-12 (CO)-C-13. The rate constants for the reactions (CH2)-C-12 (CO)-C-13 half arrow right over half arrow left (CH2)-C-13 (CO)-C-12 and (CD2)-C-12 half arrow right over half arrow left (CD2)-C-13 (CO)-C-12 are reported as a function of energy with a resolution of 1 cm-1. The rate constants exhibit pronounced peaks as a function of energy near the reaction threshold. This structure is attributed to quasistable motion along the reaction coordinate in the vicinity of the isomerization transition state.