Fluorescence lifetime measurement with pulsed excitation

The inspected apparatus sends picosecond diode-laser pulses into a sample cuvette. A neutral attenuation filter keeps detected events rare; an emission cut-off filter rejects scattered excitation. Collection optics deliver fluorescence to a photodetector; detector pulses and the laser-driver synchronization signal feed the timing electronics. The illustrated arrangement uses a PDL 800-B driver and TimeHarp 200 electronics. The note's recorded comparison uses two dye solutions and a prompt instrument-response trace; the dye tails have distinct slopes on a logarithmic display. Its Figure 9 measurement specifies an 80 MHz source, separately from the Figure 8 driver-setting example.^[ref]

For a defensible new measurement, separately acquire detector background with excitation blocked, a solvent/container blank under excitation, and a prompt response appropriate to the timing channel. Compare successively attenuated acquisitions to expose pile-up; compare early and late acquisition intervals to expose photobleaching. Choose a repetition period long enough for the relevant decay or include residual population from earlier pulses in the model. These are proposed checks, not additional controls claimed for the published curves. Photon shot noise, background mismatch, and uncertainty in the fluorescence instrument response limit how uniquely multiple decay components can be inferred.