ABSOLUTE RATE CONSTANTS, REACTIVE CROSS-SECTIONS AND ISOTOPIC BRANCHING RATIO FOR THE REACTION OF O(D-1) WITH HD Academic Article uri icon

abstract

  • Using the laser photolysis vacuum-UV laser-induced fluorescence ‘pump-and-probe’ technique, Doppler profiles of H and D atoms from the reaction O( 1 D) + HD were measured under single-collision conditions, O( 1 D) atoms were generated by laser photolysis of N 2 O at 193 nm. With a calibration method using HCl photolysis as a source of well defined H atom concentrations the following absolute rate constants k and absolute reactive cross-sections σ R have been determined: k = (1.3 ± 0.3) × 10 −10 cm 3 s −1 molec −1 and σ R (0.14 eV) = 4.0 ± 0.9 A 2 for the reaction channel O( 1 D) + HD → OD + H, and k = (1.0 ± 0.3) × 10 −10 cm 3 s −1 molec −1 and σ R (0.14 eV) = (3.0 ± 0.7) A 2 for the reaction channel O( 1 D) + HD → OH + D. The isotopic branching ratio for the reaction O( 1 D) + HD was measured directly to be Γ H/D = 1.35 ± 0.20. In addition, from the measured H and D atom Doppler profiles the fraction ƒ T of the available energy released as translational energy was determined for the individual product channels to be ƒ T (OD + H) = 0.41 ± 0.07 and ƒ T (OH + D) = 0.32 ± 0.05.

publication date

  • January 1, 1995