Rate coefficient for the BrO + HO2 reaction at 298 K

Abstract

The kinetics of the BrO + HO₂reaction (1) have been studied using the technique of flash photolysis/time resolved UV absorption spectroscopy. BrO and HO₂ radicals were generated via the Br + O₃ and Cl + CH₃OH/O₂ methods respectively. The rate coefficient for the reaction was found to be k₁ = (2.35 ± 0.82) × 10⁻¹¹ molecule⁻¹ cm³ s⁻¹ at 298 K and 760 Torr O₂. Uncertainty limits correspond to combined 2 standard deviation statistical variation and systematic factors. This result is briefly compared with previous determinations of k₁. A study of the enhancement of the HO₂ self-reaction rate in the presence of methanol was also performed, with the observed second-order loss rate coefficient given by k_obs = (2.9 × 10⁻¹² + αβ[CH₃OH])/(1 + α[CH₃OH])², with α = (6.15 ± 0.90) × 10⁻¹⁹ molecule⁻¹ cm³ and β = (3.2 ± 0.5) × 10⁻¹¹ molecule⁻¹ cm³ s⁻¹ at 298 K and 760 Torr O₂, for [CH₃OH] ⩽ 5.5 × 10¹⁷ molecule cm⁻³.