Charge transfer in the photodissociation of metal ion-benzene complexes

Photodissociation dynamics, spectroscopy, and binding energetics are investigated for a variety of gas-phase metal ion-benzene complexes. These complexes are produced and cooled by pulsed laser vaporization in a seeded supersonic expansion. They are mass-selected and studied with laser photodissociation in a reflectron time-of-flight mass spectrometer. A prominent photoprocess for many of these complexes at low energy is "dissociative charge transfer", which produces the benzene cation photofragment. The relative importance of this channel depends on the energy of excitation and on the density of metal ion electronic states in the same energy region as the charge-transfer electronic state. The measurement of the appearance threshold for the charge-transfer channel establishes an upper limit for the metal ion-benzene dissociation energy.