Absolute rate of the reaction of bromine atoms with ozone from 200 to 360 K

The rate constant for the reaction Br+O3→BrO+O2 has been measured from 200 to 360 K by the technique of flash photolysis coupled to time resolved detection of bromine atoms by resonance fluorescence (FP–RF). Br atoms were produced by the flash photolysis of CH3Br at λ≳165 nm. [03] was monitored continuously under reaction conditions by absorption at 253.7 nm. At each of five temperatures the results were independent of substantial variations in [O3], total pressure (Ar), and limited variations in flash intensity (i.e., initial [Br]). The measured rate constants obey the Arrhenius expression, k = (7.74±0.50) ×10−12 exp(−603±16/T) cm3 molecule−1 s−1, where the error quoted is two standard deviations. The results are compared with previous determinations which have employed the discharge flow–mass spectrometric technique.