$laser diffraction vs dynamic light scattering$

However, any kind of recalculation will introduce an error that adds to the initial one related to the assumption of spherical particles. When using the dynamic light scattering technique, it is possible to recalculate the volume-weighted distribution as well as D-values. To decrease the deviation, the same weighting model should be used for comparison. The DLS particle size analysis technique and laser diffraction method provide results which are based on different equivalent diameters and weighting models.įor many samples, then, results measured with DLS and laser diffraction are not directly comparable and a deviation of 10 % or more between the results is to be expected. Is it possible to compare DLS results with laser diffraction results? Which parameters should be compared? aerodynamic, hydrodynamic, optical, electrical) to that of the investigated non-spherical particle. *According to the IUPAC definition, the equivalent diameter of a non-spherical particle is equal to a diameter of a spherical particle that exhibits identical properties (e.g. The refractive index does not have any function in this case. Recalculation of the volume-based distribution to a surface- and number-based one is possible. Recalculation of the intensity-based distribution to a number- and volume-based one is possible when the refractive index of the particles is known. Peak analysis (area under the curve, standard deviation).D, mean volume diameter (De Brouckere Mean Diameter).Polydisperse sample: Peak analysis of particle size distribution graph.The particle’s contribution relates to its volume equivalent to mass for constant density.Intensity fluctuations of scattered light.In this case, the cross-sectional area becomes nearly the same as that of a sphere with equal volume (2).For particles ≤0.1 µm, the definition can be extended into volume-equivalent diameter.Laser diffraction equivalent diameter: diameter of a sphere having on the cross-sectional area the same diffraction pattern as the investigated particle (1).Where kB is the Boltzmann constant, T the absolute temperature, and η the viscosity of the liquid medium, D is the translational diffusion coefficient Diameter of a sphere with the same translational diffusion coefficient D as the particle in the same fluid under the same conditions, defined via the Stokes-Einstein equation:.The final particle size distribution is obtained from the sum of diffraction patterns produced by the particles randomly oriented along the direction of the laser beam.angle (diffraction pattern) is a function of the particle size The diffracted/scattered intensity vs.The movement of dispersed particles causes intensity fluctuations of scattered light, which are measured and converted to particle size and particle size distribution (Stokes-Einstein equation).The velocity of particle movement is a function of the particle size.

$laser diffraction vs dynamic light scattering$

Laser diffraction vs dynamic light scattering