Rate constant of the BrO + BrO reaction over the temperature range 220‐950 K

The kinetics of the self‐reaction of BrO radicals has been studied over a wide temperature range ( T  = 220‐950 K) at 2 Torr total pressure of He using a low‐pressure flow reactor combined with a quadrupole mass spectrometer: BrO + BrO → 2Br + O 2 (1a) and BrO + BrO → Br 2 + O 2 (1b). The overall rate constant for this reaction (defined by d [BrO]/ dt  = –2 k 1 [BrO] 2 ) was found to be k 1  =  k 1a + k 1b  = (1.32 ± 0.09) × 10 −12 exp(182 ± 22/ T ) cm 3 molecule −1 s −1 at T  = 220‐950 K (where the uncertainties represent precision at the 2σ level). The channel‐specific rate constant for the Br 2 + O 2 forming channel (1b) was determined at T  = 220‐450 K: k 1b  = (2.83 ± 0.35) × 10 −13 exp(34 ± 36/ T ) cm 3 molecule −1 s −1 (with 2σ uncertainties). As a result of the comparative analysis of the present data and those from the previous studies, the following Arrhenius expressions are recommended from the present work: k 1  = 1.4 × 10 −12 exp(200/ T ) at T  = 220‐950 K (independent of pressure at least for T ≥ 250 K) and k 1b  = 3.2 × 10 −13 exp(34/ T ) cm 3 molecule −1 s −1 at T  = 220‐450 K and total pressure of 2 Torr, with a conservative estimate of uncertainty of 25%, independent of temperature.