Radiation damage in dry and frozen hydrated organic material

Abstract

SUMMARYElectron‐induced radiation damage can cause errors in interpreting electron micrographs. Radiation damage is distinguished from contamination (polymerization of hydrocarbons) and etching (radiolysis in the presence of water), both of which can be controlled by a proper specimen environment in the microscope. While temperature has little effect on the primary interactions of fast electrons with matter, most secondary radiation‐damage processes are temperature dependent. Because damage mechanisms differ so greatly among materials, there is no simple factor by which specimen stability is improved as a function of temperature (some cases improve fivefold, others improve 100‐fold). While some specimens are stable to almost arbitrarily high doses, some tests reveal damage at 1 e/nm2. This paper surveys damage rates and temperature dependencies of various materials as a guide for future electron microscopic studies of organic specimens.