Temperature-Dependent Rate Coefficients for the Reactions of Br(2P3/2), Cl(2P3/2), and O(3PJ) with BrONO2

A laser flash photolysis−resonance fluorescence technique has been employed to investigate the kinetics of reactions of the important stratospheric species bromine nitrate (BrONO 2 ) with ground-state atomic bromine ( k 1 ), chlorine ( k 2 ), and oxygen ( k 3 ) as a function of temperature (224−352 K) and pressure (16−250 Torr of N 2 ). The rate coefficients for all three reactions are found to be independent of pressure and to increase with decreasing temperature. The following Arrhenius expressions adequately describe the observed temperature dependencies (units are 10 -11 cm 3 molecule -1 s -1 ): k 1 = 1.78 exp(365/ T ), k 2 = 6.28 exp(215/ T ), and k 3 = 1.91 exp(215/ T ). The accuracy of reported rate coefficients is estimated to be 15−25% depending on the magnitude of the rate coefficient and on the temperature. Reaction with atomic oxygen is an important stratospheric loss process for bromine nitrate at altitudes above ∼25 km; this reaction should be included in models of stratospheric chemistry if bromine partitioning is to be correctly simulated in the 25−35 km altitude regime.