Dynamic Light Scattering (DLS)

Dynamic Light Scattering (DLS)

Dynamic Light Scattering (DLS) measures the average size and size distribution of particles and colloids in solutions. Particles suspended in a liquid are constantly undergoing Brownian (random) motion, and the size of these particles directly affects their speed: smaller particles move faster than larger ones.

A laser light source is applied to the sample which scatters as it passes around any particles or colloids in its path. The scattered light is detected and recorded at some pre-defined angles. The time dependence of the scattered intensity can be correlated to particles speed, allowing simultaneous measurement of average size and size distribution of particles in the system.

What DLS is great for:

  • Particle size as a function of time, temperature, concentration and pH
  • Formulation development, process development
  • Average size and size distribution of dispersion, emulsion and suspension
  • Performance-related parameters such as refractive index, transmittance, opaqueness, transparency
  • Dosing and titration monitor, settling and aggregation indicator
Our technical team is happy to clarify on what technique will provide you with the best data.

EXAMPLE OUTPUTS 

DLS Anton Paar
DLS of a trimodal polystyrene latex sample containing particles of 22, 100 and 700nm in the ratio of 3:1:1. Credit: Anton Paar

INSTRUMENTS USED FOR
DLS

Anton Paar Litesizer™ 500

The Litesizer 500 has been optimized to characterize nano- and micro- particles in dispersions and solutions. It includes advanced analytical tools able to distinguish between several particle sizes present within the same sample, and has highly accurate detector systems to facilitate parallel measurement of the refractive index of the material at the exact wavelength and temperature used during DLS analysis.