Simulations and experiments on number fluctuations in photon-correlation spectroscopy at low particle concentrations

At low particle concentrations number fluctuations in photon-correlation spectroscopy measurements lead to a slow decay in the autocorrelation function, which contains information about the concentration. The characteristic time tau (c) of this number-fluctuation decay depends on the size of both the particle and the scattering volume. For determination of the concentration a measurement should last for at least a time of 100 tau (c). Using Brownian dynamics simulations and measurements, we have studied the effects of the measurement time on the decay of the number fluctuations. (C) 2001 Optical Society of America.