Kinetics of the reactions of O(3P) and Cl(2P) with HBr and Br2

A laser flash photolysis-resonance fluorescence technique has been employed to study the kinetics of reactions (1)–(4) as a function of temperature. In all cases, the concentration of the excess reagent, i.e., HBr or Br₂, was measured in situ in the slow flow system by UV-visible photometry. Heterogeneous dark reactions between XBr (X = H or Br) and the photolytic precursors for Cl(²P) and O(³P) (Cl₂ and O₃, respectively) were avoided by injecting minimal amounts of precursor into the reaction mixture immediately upstream from the reaction zone. The following Arrhenius expressions summarize our results (errors are 2σ and represent precision only, units are cm³ molecule^?1 s^?1): ??₁ = (1.76 ± 0.80) × 10^?11 exp[(40 ± 100)/T]; ??₂ = (2.40 ± 1.25) × 10^?10 exp[?(144 ± 176)/T]; ??₃ = (5.11 ± 2.82) × 10^?12 exp[?(1450 ± 160)/T]; ??₄ = (2.25 ± 0.56) × 10^?11 exp[?(400 ± 80)/T]. The consistency (or lack thereof) of our results with those reported in previous kinetics and dynamics studies of reactions (1)–(4) is discussed.