Resolution of Individual Component Fluorescence Lifetimes from a Mixture of Trapped Ions by Laser-Induced Fluorescence/Ion Cyclotron Resonance

We have measured the fluorescence lifetime (τ) of both pure C 6 F 5 H + and pure C 6 F 3 H 3 + confined in an open cylindrical (ICR) Penning trap as 44 ± 2 ns and 51 ± 2 ns, respectively, consistent (∼10%) with prior literature values in the absence of ion trapping and magnetic field. For an equimolar mixture of C 6 F 5 H + and C 6 F 3 H 3 + the effective lifetime, τ eff, was 47 ± 2 ns. Ion cyclotron-resonant azimuthal quadrupolar excitation successfully isolated either C 6 F 5 H + or C 6 F 3 H 3 + ions from the mixture, each with the same fluorescence lifetime as from a pure sample. The signal-to-noise ratio, ∼94:1, demonstrates the feasibility of observing fluorophores of lower quantum yield, such as tryptophan. This work represents the first determination of fluorescence lifetimes of organic ions in a Penning trap, and demonstrates the feasibility of resolving fluorescence from individual species in a chemically heterogeneous mixture by mass-selective ion cyclotron resonance.