Reactive scattering of hydroxyl radicals : OH + Br2

Abstract

Angular and velocity distribution measurements of HOBr reactive scattering from crossed beams of OH radicals and Br2 molecules are reported. The OH radical beam was generated by the reaction of H atoms, formed in a microwave discharge through a low pressure flow of H2, with NO2 gas in a pyrex mixing source. The Br2 beam was generated from a supersonic nozzle source at ∼400 K with a stagnation pressure ∼100 Torr. Product velocity distributions were measured at each laboratory scattering angle by the cross-correlation time-of-flight method. The scattering data are found to be in good agreement with the RRKM-AM model of reactive scattering via a long-lived collision complex, with similar parameters to the O + Br2, I2 reactions. This indicates the existence of an HOBrBr collision complex, whose stability and possible structure are rationalized in terms of Walsh molecular orbital theory.