Photodissociation and collisional cooling of rhodamine 575 cations in a quadrupole ion trap.

The photodissociation of rhodamine 575 cations held in a quadrupole ion trap is studied using 514 nm light as a function of buffer gas pressure, irradiation time, and laser fluence. The laser-induced photodissociation decays of rhodamine ions have lifetimes on the order of seconds for the range of pressures and powers investigated and exhibit strong nonlinear pressure dependence. Dissociation mechanisms are considered that involve the sequential absorption of multiple photons and several collisional deactivation steps.