Abstracting reliable parameters from time-correlated single photon counting experiments

An investigation of how many photons need to be collected, when using the time-correlated single photon counting method, in order to reproduce, within a reasonable accuracy, the generating function of a poly-exponential decay, indicates that this number is quite often considerably greater than that usually published. This poses a series of potential problems if considerably longer counting times are used. It is proposed that the solution is to collect data with substantial pileup. An analytical expression is given for correcting the errors due to pileup in poly-exponential decay profiles. The method, which requires only a knowledge of the STOP/START ratio and the experimental decay profiles, generates results basically identical to those obtained when pileup is intentionally limited, even for high pileup distortion, thus greatly reducing the time necessary to make measurements.