Figure 3: Fluorescence decay data of tris(2,2'-bipyridyl)ruthenium(II) obtained by gating a PMT When the green signal goes low, the LED turns off. Shortly thereafter, the PMT is gated on (the red signal goes low). The fluorescent decay is seen by subtracting the baseline (blue signal) when the fluorophores is not present from the signal when the fluorophores is present (purple signal). (Only a part of the time course is shown here.)