Abstract

A radius of gyration is a particle parameter obtainable through light- or x-ray scattering in the Rayleigh-Gans-Debye regime. Radii of gyration can also be theoretically defined and experimentally obtained for scattering in the Fraunhofer diffraction dominated regime. It is shown how this applies to both oriented and disoriented scattering for particles of general shape. For oriented particles, the parameter is the root-mean-square distance from a line passing through the particle's center of mass, along the direction of intensity scanned in the plane perpendicular to the incident radiation beam direction. For disoriented particles, any scanning direction in this plane will give a root-mean-square distance from the particle's center of mass. In both cases the particle is represented as a flat mask outline. Experimental procedures and particle properties necessary for obtaining the parameters are outlined. A simple laser procedure applicable at least to many particles in the 10-μm to 100-μm size range is described.

© 1985 Optical Society of America