Chopped-laser two-photon photodissociation measurement of collisional relaxation in benzene ion

The collisional relaxation of photoexcited benzene ions was studied through two-photon photodissociation using the chopped-laser technique in the ion cyclotron resonance (ICR) ion trap. The number of collisions required for quenching varied from 1 for benzene quench gas to 95 for helium, with the quenching efficiency increasing with size and complexity of the neutral. A comparison with quenching of bromobenzene ion by many of the same quench gases showed energy transfer from benzene ion to be about a factor of 2.5 less efficient.