Absorption coefficients and kinetics of the BrO radical using molecular modulation

Abstract BrO radicals were produced by square-wave-modulated photolysis of Br 2 O 3 mixtures and detected in absorption by molecular modulation spectrometry. The spectrum of BrO in the region 296 – 375 nm has been determined from absorption measurements at 0.1 nm intervals and with 0.22 nm resolution. A total of 17 bands in the A 2 Π ← X 2 Π system were observed and the absorbance in these bands was put on an absolute basis by measurement of the cross section for absorption at the band head of the ( v ′ = 7) ← ( v ″ = 0) transition at 338.3 nm. Kinetic studies of BrO in the modulated photolysis system yielded a rate constant for the reaction where k 5 = (6.6 ± 1.5) × 10 −13 cm 3 molecule −1 s −1 . k 5 showed no significant temperature dependence over the range 278 – 338 K.