Measurement of Decay Lifetime of Metastable Dye Molecular Ions by Using Ion Trap

We have demonstrated the existence of metastable excited rhodamine molecular ions when created in laser desorption ionization. Rhodamine ions were stored in a rf ion trap, and photodissociation was used to probe the metastable population as a function of trapping time. From the dependence of the population decay on buffer gas pressure and by extrapolating it to zero pressure we have obtained the lifetime of the metastable state of the ions in isolated condition.