![]() ![]() At high concentrations, particle-particle interactions and multiple light scattering can become dominant and can result in apparent particle sizes that differ between concentrated and dilute suspensions. However, specific requirements for the instrument setup and specification of test sample preparation are required for concentrated suspensions. This technique is commonly known as dynamic light scattering (DLS), but is also called photon correlation spectroscopy (PCS) and quasi-elastic light scattering (QELS). The principle of dynamic light scattering for a concentrated suspension is the same as for a dilute suspension. Dynamic light scattering (DLS), which is also known as photon correlation spectroscopy (PCS) or quasi-elastic light scattering (QLS), is a spectroscopy method used in the fields of chemistry, biochemistry, and physics to determine the size distribution of particles (polymers, proteins, colloids, etc.) in solution or suspension. Light Scattering Theories Rayleigh Scattering If the particles are small compared to the wavelength of the laser used (typically less than d ยช 10 or around 60nm for a He-Ne laser), then the scattering from a particle illuminated by a vertically polarised laser will be essentially isotropic, i.e. Dynamic Light Scattering Technology Particle size can be determined by measuring the random changes in the intensity of light scattered from a suspension or solution. ISO 22412:2017 is applicable to the measurement of a broad range of dilute and concentrated suspensions. ![]() DLS is also referred to as "quasi-elastic light scattering (QELS)" and "photon correlation spectroscopy (PCS)," although PCS actually is one of the measurement techniques. ISO 22412:2017 specifies the application of dynamic light scattering (DLS) to the measurement of average hydrodynamic particle size and the measurement of the size distribution of mainly submicrometre-sized particles, emulsions or fine bubbles dispersed in liquids. ![]()
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