Mapping Reaction Dynamics via State-to-State Measurements:  Rotations Tell the Tale

We describe a series of experiments and computational simulations of the state-to-state dynamics of the atom transfer reactions H + HX → H2(v‘,j‘) + X (HX = hydrogen halide) and H + RH → H2(v‘,j‘) + R (RH = alkane). The rotational and vibrational state distributions of the H2 products are characterized for reaction at well-defined initial conditions. The vibrational state distributions provide some information. However, it is the rotational state distributions that form the basis for mapping the path from reactants to products. In analyzing these state distributions, we develop a method that takes explicit, quantitative account of kinematic constraints on the product energy disposal. This method is generally applicable to bimolecular reactions and provides a context in which to interpret the rotational and vibrational state distributions.