Time-interval statistics applied to the analysis of low-polydispersity samples for low light-intensity levels

A time-interval-statistics method that is based on the measurement of the Laplace transform of the probability function of the time intervals between two successive photoelectrons has been applied to experiments of light diffusion from low-polydispersity samples from which the scattered intensity is weak (less than 1 photoelectron/characteristic fluctuation time). Computer-simulation methods have been used to simulate intensity fluctuations and positions of individual photoelectrons for different experimental situations. The parameters characterizing the diffusion-coefficient distribution function of the sample (mean and index of polydispersity) and their corresponding errors are obtained and analyzed as a function of the mean intensity and the polydispersity index.