Time-Resolved Photodissociation Rates and Kinetic Modeling for Unimolecular Dissociations of Iodotoluene Ions

Article abstract of DOI:10.1021/j100056a001

Time-resolved photodissociation rate measurements are reported for the unimolecular dissociation of the three iodotoluene ion isomers at two values of internal energy (2.54 and 2.67 eV).For the para isomer, the rate constants are in agreement with previous experimental information.The meta isomer is roughly similar to para, but the ortho isomer dissociates roughly 5 times faster at the same internal energies.These new data, along with prior results, are fitted into a comprehensive two-channel model of the dissociation kinetics, assuming competitive dissociation to form tolyl ions, and either benzyl or tropylium ions.Activation energies and entropies are assigned to both dissociation channels for each isomer.This two-channel model accounts satisfactorily for most of the experimental information available about these dissociation processes, and possible explanations are advanched to explain discrepant data.