Reaction products with internal energy beyond the kinematic limit result from trajectories far from the minimum energy path: An example from H + HBr → H₂ + Br

The importance of reactive trajectories straying far from the minimum energy path is demonstrated for the bimolecular reaction H + HBr → H₂(v-, j-) + Br at 53 kcal/mol collision energy. Product quantum state distributions are measured and calculated using the quasi-classical trajectory technique, and the calculations indicate that highly internally excited H₂ products result from indirect reactive trajectories with bent transition states. A general argument is made suggesting that reaction products with internal energy exceeding a kinematic constraint can, in general, be attributed to reactive collisions straying far from the minimum energy path.