Nanoparticle Size measurement using Dynamic Light Scattering

DLS uses Brownian motion of nanoparticles (NPs) in a solvent in order to measure their size distribution. Launching a laser into the particles and looking at the scattering light in a specific direction allows to analyse the NPs size distribution.

schema dynamic light scattering system - VASCO FLEX
schema Brownian motion - dls

Scattering light is detected and a real-time correlator is applied to this signal in order to set a correlogram graph. This graph is the signature of the particle size movement in the solvent.

Correlogram - size distribution

Three Mathematical algorithms are then used in order to get the real size distribution from the experimental correlogram. Cumulant is assuming that there is only one main size of NPs with a specific Gaussian distribution, Padé-Laplace is assuming that there is a discrete number of different sizes and SBL is looking for multi-modal and multi dispersity size distribution.

DLS _ three Correlograms - size measurement