Product state distributions from the reaction O(3P)+ HBr

Abstract

An experimental investigation has been performed of the hydrogen atom abstraction reaction O(³P)+ HBr → OH(X²Π)+ Br. A photolytic method was used to produce O(³P) in the presence of HBr, and laser-induced fluorescence detection employed to obtain the nascent vibrational, rotational and fine-structure state partitioning in the product OH. Distributions were found to be highly internally excited, with a strong vibrational inversion and substantial rotational excitation, extending to the limit of available energy. Non-statistical distributions of the fine-structure states were observed. The possibility of a subsidiary reactive channel producing spin–orbit excited Br(²P_1/2) is proposed as an explanation for an apparent anomaly in the OH(v″= 1) rotational distribution. The dynamics generally appear consistent with the kinematic constraints imposed by the heavy + light–heavy mass combination.