= 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.<Time-Correlated Single Photon Counting (technical note v. 2.1) by Michael Wahl>[Michael Wahl, Time-Correlated Single Photon Counting, v. 2.1, pp. 7–9, Figures 8–9: cuvette/filter/detector setup; Toluidine Blue and Oxazin 4 curves; explicit 80 MHz measurement setting]{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.
Back to article page
