![]() The ACF can be evaluated by the CONTIN algorithm according to Provencher ( 1982), which allows to fit even a complex decay of correlation in polydisperse solutions to calculate the respective diffusion constants (D) and process the data. ![]() Decay time constants of small particles are shorter in agreement with the dependency of diffusion speed on particle mass (Fig. Depending on how fast particles are diffusing, the correlation decay time constants, which are derived from the exponential auto-correlation function (ACF) are individually different. Scattering intensity pattern are correlated with themselves (auto- correlation) after short delay intervals of time (τ) to monitor the continuous decay of correlation. 6.2), which results in characteristic size- dependent fluctuation intervals of the electric field component of the scattered light. This is explained by Brownian motion of particles in and around the sample volume that is in focus of the laser (Fig. The number of photons hitting the detector, which can be a photo-multiplier tube, is fluctuating over time. The laser light that is scattered by the particles inside a small focal volume of a DLS sample is continuously recorded and quantified by a photon-counting detector positioned at a specific angle if not hindered by other geometrical restraints, an angle of 90° might be suitable for the experimental setup. In general, all kinds of particles scatter electromagnetic waves in all directions, depending on their size isotropically or anisotropically.
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