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 (tau) of both pure C6F5H+ and pure C6F3H3+ confined in an open cylindrical (ICR) Penning trap as 44 +/- 2 ns and 51 +/- 2 ns, respectively, consistent (similar to10%) with prior literature values in the absence of ion trapping and magnetic field. For an equimolar mixture of C6F5H+ and C6F3H3+ the effective lifetime, tau(eff), was 47 +/- 2 us. Ion cyclotron-resonant azimuthal quadrupolar excitation successfully isolated either C6F5H+ or C6F3H3+ ions from the mixture, each with the same fluorescence lifetime as from a pure sample. The signal-to-noise ratio, similar to94:1, 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.