Dynamic light scattering (DLS), also known as photon correlation spectroscopy (PCS), is a commonly used characterization method for nanoparticles. DLS particle size analyzer has the advantages of accuracy, rapidity, and good repeatability.
With the update of the instrument and the development of data processing technology, the current dynamic light scattering instrument not only has the function of measuring particle size, but also has the ability to measure Zeta potential and molecular weight of large molecules.
The principle of DLS of dynamic light scattering is that nano-particles, emulsion droplets and molecules in suspension are also moving in a similar way under the collision of Brownian motion of liquid molecules. When a laser strikes these dynamic particles or molecules, these moving particles cause a fluctuation in the intensity of the scattered light, and the frequency of the fluctuation depends on the velocity of the particle, which depends on the size of the particle (because the smaller the particle size, the faster it moves under the impact of the particle Brownian motion).
Therefore, the velocity of particle Brownian motion will be obtained by analyzing the intensity fluctuation of scattered light, and the particle size and particle size distribution of nanoparticle can be obtained by using Stokes-Einstein equation.