A-1995A: The Sizing of Non-Spherical, Sub-Micron Particles Using Polarization Intensity Dfferential Scattering (PIDS)

Nearly all laser-based particle-sizing devices make no allowance for the shape of the materials under test, regardless of the size of the particles. The reason for this lies with the underlying assumptions used for calculating size distributions from the raw data generated during the analysis. The mathematical models used to calculate distributions are based on spherical systems. So any reported distribution is, in effect, an equivalent spherical distribution of the material being analyzed. In most instances, this is quite adequate since most particles approximate to a spherical system adequately enough. The LS Series multi-wavelength particle size analyzers from Beckman Coulter, Inc. utilize a complementary scattering technology for the sizing of sub-micron particles. This technical note will describe, by reference to real samples, how nonspherical particles are sized using the PIDS system. Why PIDS?