Scanning electron microscope autoradiography. A technique for the location and study of microscopic beta-active particles.

Abstract

The technique of scanning electron microscope autoradiography (SEMA) has been adopted and developed for the location and detailed study of individual microscopic particles of radioactive beta-emitting material. Samples of particulates collected on Nuclepore filters are coated with a thin layer of liquid photographic emulsion and, after development, any active particles can be readily identified by scanning electron microscope (SEM) observation of their surrounding distribution of exposed silver grains. As well as providing the means of location, the grain distribution can be analyzed to provide estimates of both the particle activity and the energy of the emitted beta-particles. The technique is particularly well suited to the study of particles in the submicron and micron size range. A knowledge of the elemental composition of the identified active partic1es can also be obtained in situ by energy dispersive X-ray spectroscopy (EDS) and the use of an SEM makes the technique readily amenable to on-line image analysis.