CO(V,J) PRODUCT STATE DISTRIBUTIONS FROM THE REACTION O(3P)-]CO+SO(OCS)

The title reaction was studied by probing CO[upsilon,J] product state distributions with a tunable infrared diode laser. Only the fastest O( 3P) atoms formed by 355 nm photolysis of NO2, i.e., Those correspondin g to NO[2PI1/2, upsilon = 0], have sufficient energy to surmount the a ctivation barrier. Thus these experiments were performed under monoene rgetic, near-threshold conditions. The CO[upsilon,J] distributions wer e extracted from the relative slopes of the transient infrared absorpt ion signals. Little vibrational excitation is observed. The vibrationa l branching ratio is [upsilon=1]/[upsilon=0]almost-equal-to 0.05; CO[u psilon greater-than-or-equal-to 21 was not detected. In contrast, rota tional degrees of freedom are much hotter. The nascent CO[upsilon = 0] rotational distribution is well characterized by a temperature of T(R )=4400+/-390 K. Total CO internal excitation, on the average 3150 cm-1 , accounts for 16% of the energy available to products. Surprisal anal yses based on several models of energy disposal show that the nascent distributions are nonstatistically cold. The results are consistent wi th direct attack at the S atom to firm an OSCO intermediate, followed by rapid C-S bond scission which exerts a torque on the CO product.