DOPPLER-RESOLVED LASER PROBING OF PHOTON-INITIATED BIMOLECULAR COLLISIONS O(D(1))-]OH(V,N)+CH3(CH4)

The stereodynamics of the reaction O(1D) + CH4 --> OH(nu less-than-or- equal-to 4,N) + CH3 at collision energies of approximately 40 kJ mol-1 , has been probed via Doppler-resolved, polarized laser-induced fluore scence spectroscopy. Velocity-aligned, reagent O(1D) atoms were genera ted under bulb conditions via polarized laser photodissociation of N2O . Analysis of the Doppler profiles of nascent OH(nu,N) fragments has a llowed both scalar and vectorial product correlations to be determined , including differential scattering cross sections and rotational alig nments. These imply the operation of a 'delayed' collision mechanism, dominated by the deeply attractive potential energy surface associated with the insertion to form CH3OH; the intermediacy of a long-lived co mplex is excluded, however. Rotational angular momentum in the recoili ng OH fragments is preferentially aligned perpendicular to, and azimut hally distributed about, their recoil velocity. The rotational excitat ion is thereby attributed to bending motion in the C...O...H plane dur ing the reagent collisions. The scalar product pair correlations estab lish a near-zero translational exoergicity and anticorrelated internal energy distributions in the two reaction products.