Dynamic Light Scattering Spectrophotometer DLS-8000 series Principle

Particulates dispersed in a solution are normally subject to Brownian motion. The motion is slower with larger particles and faster with smaller particles. When laser light illuminates particles under the influence of Brownian motion, scattered light from the particles shows fluctuation corresponding to individual particles. The fluctuation is observed according to the pinhole type photon detection method so that particle size and particle size distributions are calculated.

Static Light Scattering Method is renowned as the convenient method to know absolute molecular weight. As a principle, molecular weight is calculated from absolute value of scattered light obtained by irradiated light into colloidal particle. To simplify, from the bigger particle gives the stronger scattering and the smaller particle gives weaker scattering. In reality, scattering intensity to be obtained depends upon concentration, too. So the plotting concentration on horizontal and Kc/R(θ), which is equivalent as a reciprocal number of scattering intensity, on vertical after measuring scattering intensities of variable concentrations is called Debye Plot.Since angle dependency of scattering intensity appears in the large molecular weight sample, measuring scattering intensity at variable angle(θ) provides more accuracy on molecular weight measurement and radium of gyration, which is yardstick of molecular dispersion.When measured at fixed angle, inputting expected radium of gyration, correcting as an angle dependent measurement, accuracy of molecular weight is improved.