Dynamic Light Scattering - DLS

Dynamic Light Scattering or DLS measures particle size and size distribution of particles in liquid suspension. The Brownian motion of particles or molecules causes laser light to be scattered at different intensities. Analysis of these intensity fluctuations yields the velocity of the Brownian motion and hence the particle size using the Stokes-Einstein relationship.


  1. The nanoparticle sample is inserted into the path of the laser inside a cuvette.
  2. The laser beam passes through the sample and photons are scattered in all directions. As the particles move the detected intensity of the photons changes over time.
  3. These changes in intensity are recorded by the photon counting device and this information is then correlated identifying how quickly the intensities fluctuate.
  4. Fast fluctuations correspond to fast diffusion of particles and slow fluctuations to slow diffusion.
  5. The Stokes-Einstein relationship is then used to convert the diffusion rates of the particles into an average size and a size distribution.

 Used in


Aggregation rate determination


Read more

Read also



ISO22412 (2017) Particle size analysis - Dynamic Light Scattering (DLS)




Jake Austin


Email: Jake.Austin@malvern.com