The dynamics of the light atom transfer reaction O(3PJ) + HBr → OH(′, j′) + Br(2PJ′ )

Abstract

The dynamics of the title light-atom transfer reaction have been investigated using laser pump and probe techniques at a mean collision energy close to 0.3 eV. The experiments employed 308 nm photodissociation of NO₂ to generate translationally excited O(³P) atoms, and were conducted at room temperature. OH quantum state populations were found to be in excellent accord with those determined by McKendrick et al. [Faraday Discuss. Chem. Soc., 1987, 84, 39]. OH Doppler resolved laser induced fluorescence was used to determine the angular distribution of the scattered OH products. For OH(²Π_3/2, A′) born in (′ = 1, N′ = 5) the angular distribution was found to be broad, but peaked towards the forward direction, consistent with expectation based on kinematic considerations. More interestingly, a consistent fit to the experimental data could only be achieved by assuming that 10% of the OH(′ = 1, N′ = 5) products are partnered by spin–orbit excited state Br(²P_1/2) atoms. The data suggest that at comparable energies above their respective energetic thresholds, the reaction cross-sections for production of OH(²Π_3/2, A′, ′ = 1, N′ = 5) in conjunction with Br and Br* are similar.