The dynamics of the OH + HD gas-phase reaction: Absolute reaction cross section and H/D atom product branching ratio

Article abstract of DOI:10.1016/S0009-2614(97)00719-7

The dynamics of the OH + HD reaction were studied in the gas-phase using the laser photolysis/vacuum-UV laser-induced fluorescence pump-and-probe technique. Translationally energetic OH(²II) radicals with an average reagent translational energy of E_c.m. = 0.24 eV in the (OH-HD)-center-of-mass system were generated by the laser photolysis of H₂O₂ at 248 nm. Doppler profiles of nascent D and H atoms produced in reactive collisions of OH with room-temperature HD molecules were detected under single-collision conditions by VUV-LIF at the Lyman-α transition. For the OH + HD reaction an absolute reaction cross section of σr_R(0.24 eV) = (0.14 ± 0.05) A² was determined by means of a calibration method using OH + D₂ as a reference reaction. The branching ratio for the OH + HD → H + HOD (D + H₂O) product channels was measured to be Γ_H/D = (1.2 ± 0.2).