Time-resolved IR chemiluminescence from reactive collisions between hydrogen atoms and SO₂

We report the first observation of time-resolved IR emission from the rovibrationally excited OH produced in the H + SO₂ reaction. H atoms were produced via 193 nm photolysis of HBr. Low-resolution emission spectra were collected over the 4000-2800 cm^-1 spectral region. The high degree of internal excitation deduced from the spectral emission indicates that, unlike similar reactions of this type, the ground state HOSO complex exerts little, if any, influence on the dynamics of this reaction. Quasi-classical trajectory calculations assuming a quasi-triatomic approximation for HSO₂ have also been performed, and these results in conjunction with previous ab initio studies lead to a cohesive model of the reaction dynamics of this tetra-atomic system.