KINETICS AND MECHANISM OF THE BRO+HO2 REACTION

Using the discharge flow-mass spectrometric technique, the kinetics an d mechanism of the BrO + HO2 reaction have been investigated in the te mperature range 233-344 K. With an excess of HO2 over BrO, the rate co nstant was found to be k(1) = (4.77 +/- 0.32) x 10(-12) exp[(580 +/- 1 00)/T] cm(3) molecule(-1) s(-1). The reaction may proceed via two chan nels: BrO + HO2 --> HOBr + O-2 (1a) and BrO + HO2 --> HBr + O-3 (1b). Over the whole temperature range, HOBr was observed as the major produ ct, whereas an upper limit was measured for channel 1b from the absenc e of detection of O-3: k(1b)/k(1) < 1.5%. The potential implications o f these data are briefly discussed in relation to the stratospheric br omine/ozone interaction.