TRANSITION-STATE SWITCHINGS FOR SINGLE POTENTIAL WELL IONIC DISSOCIATIONS

Microcanonical variational transition state theory calculations were applied to the reaction C6H5Br.+ --> C6H5+ + Br. in bromobenzene. Calculations were compared with experimental results for C6H5+ time-resolved photoionization efficiency curves and available k(E) data for this system. Calculations demonstrate, in agreement with previous results for CH4.+, that multiple transition states are possible for single-well potentials of ionic systems. However, comparison with experiments indicates the dominance of the orbiting transition state over a wide energy range above threshold. Further extension of k(E) measurements to higher energies is recommended, in order to be able to confidently rule out transition-state switching to a tight transition state as E increases.