Fig. 6.2.

DLS determines particle sizes based on the velocity of Brownian motion: a Generalized illustration of the time-dependent intensity of light scattered by particles, which is fluctuating due to Brownian motion. Mixtures of small and large particles would result in a weighted average of the two displayed scattering intensity pattern. b Schematic illustration of the auto-correlation. Depending on the particle size, the diffusion speed and hence the time scale of the correlation coefficient decay is varying. Accordingly two auto-correlation functions (g(τ)) for a small (green) and a larger (blue) particle species are shown on the right side