Quantum state-resolved reactive scattering of F+CH_4- HF(v, J)+CH_3: Nascent HF(v, J) product state distributions

摘要

State-to-state reactive scattering of F+CH,4—~HF( v ,J) + CH3 is studied using crossed supersonic jets and high-resoluhon (A v~ 0.0001 cm 1) IR laser direct absorption techniques. Rovibrational state-resolved HF column-integrated absorption profiles are obtained under single collision conditions and converted to populations via appropriate density-to-flux transformation. Nascent rovibrational distributions in each HF(v ,J) state are reported. Summed over all product rotational levels, the nascent vibrational quantum state populations for HF(v) [(v=3) 0.106(3); (v =2 0.667(14); (v1) 0.189(27); (v0) 0.038(78); 2o- error bars] are in agreement with previous flow cell studies by Setser, Heydtmann, and co-workers fChem. Phys. 94. 109 (1985)]. At the rotational state level, however, the current studies indicate nascent distributions for HF( v , J) that are significantly hotter than previously reported. ostensibly due to reduced collisional relaxation effects under supersonic jet conditions. Final HF rotational states from F+CH4 are observed near the maximum energetically accessible J values in both the v 2 and v 3 vibrational manifolds, which provides experimental support for a bent F—H—C transition state structure.