Size Analysis and Identification of Particles

Publisher Summary This chapter is focused on size analysis and identi?cation of particles, organized around the concept of equivalent spherical diameters. The particle size is discussed according to light-scattering equivalent diameter, aerodynamic equivalent diameter, hydrodynamic equivalent diameter, and other equivalent diameters. Many airborne particle count applications make use of particle counters that directly sample the air using built-in vacuum pumps to determine particle count and size distribution using the principle of light scattering. One of the standard methods for collecting particles in cleanrooms for subsequent particle count, size distribution, and chemical identi?cation is the witness plate. Dynamic light scattering can be used to determine the size-distribution pro?le of small particles in suspension. The size range of analysis ranges from a few nanometers to a few micrometers. It is found that when the concentration of particles is very small, the repeatability and reproducibility of microscope counting of irregularly shaped particles can limit its value as a referee particle-counting technique.