Measurement principle and function of dynamic light scattering method

Dynamic light scattering, also called photon correlation spectroscopy, is a conventional nanoparticle size characterization method with the advantages of accuracy, speed, and good repeatability. With the update of instruments and the development of data processing technology, today's dynamic light scattering instruments not only have the function of measuring force static, but also have the ability to measure Zeta potential and the molecular weight of macromolecules.

The measurement principle of dynamic light scattering is to measure nanoparticles, emulsion droplets and molecules in suspension. Due to the thermal motion of liquid molecules, the particles are subject to unbalanced collisions of liquid molecules from all directions, resulting in irregular Brownian motion. When a laser beam irradiates these dynamic particles or molecules, these moving particles will cause scattered light intensity fluctuations, and the frequency of fluctuations depends on the movement speed of the particles, and the movement speed depends on the particle size (because the smaller the particle size, the smaller the particle size. The faster the molecules move under the impact of Brownian motion), so by performing autocorrelation analysis on the fluctuating scattered light, the Brownian motion speed of the particles will be obtained, and then the Stokes-Einstein equation can be used to obtain the nanometer particle size and particle size distribution. .