Picosecond lasers time-correlated single-photon counting

Time-Correlated Single-Photon Counting. For the application of TCSPC in the picosecond time domain, lasers with pulses whose half-widths are 20 ps or less are used. For better time resolution, the combination of a microchan-nel plate photomultiplier tube (MCP-PMT) and a fast constant fraction discriminator (CFD) are used instead of a conventional photomultiplier tube (PMT). A TCSPC system with a time response as short as 40 ps has at its core a Nd YLF (neodymium yttrium lithium fluoride) laser generating 70-ps, 1053-nm pulses at... 

Figure 2.16 shows an example for such a biexponential decay measured with time correlated single-photon counting.78,75 Several picosecond laser experiments have explored this early time behavior of the equilibration... 

The rotational reorientation times of the sample in several solvents at room temperature were measured by picosecond time-resolved fluorescence and absorption depolarization spectroscopy. Details of our experimental setups were described elsewhere. For the time-correlated single photon counting measurement of which the response time is a ut 40 ps, the sample solution was excited with a second harmonics of a femtosecond Ti sapphire laser (370 nm) and the fluorescence polarized parallel and perpendicular to the direction of the excitation pulse polarization as well as the magic angle one were monitored. The second harmonics of the rhodamine-640 dye laser (313 nm 10 ps FWHM) was used to raesisure the polarized transient absorption spectra. The synthesis of the sample is given elsewhere. All the solvents of spectro-grade were used without further purification. 

Table 9.2. Fluorescence decay parameters of human hemoglobin subunits obtained with the time correlated single photon counting method using a sync-pumped picosecond dye laser as the excitation source.

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