Interpreting Laser Diffraction Results for Non-Spherical Particles

Particle shape can have a profound impact on particle size distribution (PSD) measurements. In the case of Laser Diffraction, the shape and aspect ratio of particles alter the diffraction pattern used to determine PSD, which is calculated on the basis of equivalent spherical diameter. For instance, it has been established that the reported size of an ellipsoid is always smaller than the physical major dimension of the particle. Furthermore, when non-spherical particles align within a flowing sample, laser diffraction instruments typically report a bi-modal size distribution even in the case of monodisperse samples.

Equipped with only qualitative knowledge of particle shape, the particle analyst can resolve this inherent ambiguity and use laser diffraction to obtain quantitative information (such as aspect ratio) about non-spherical particles. This webinar explains the origin of this effect, describes how to interpret PSD data in such cases, and demonstrates several practical applications for measurements of crystals, bacteria, and clays.