Description

Particles, emulsions and molecules in suspension undergo Brownian motion. If the particles or molecules are illuminated with a laser, the intensity of the scattered light fluctuates at a rate that is dependent upon the size of the particles as smaller particles are kicked further by the solvent molecules and move more rapidly. Analysis of these intensity fluctuations yields the velocity of the Brownian motion and hence the particle size using the Stokes-Einstein relationship. Dynamic light scattering is a non-invasive and well-establish technique for measuring the size of molecules and particles typically in the submicron region.