Electron diffraction study of radiation damage in coronene

The problem of radiation damage to the specimen in the electron microscope is discussed by studying the deterioration of the electron diffraction pattern of coronene. The damage is found to decrease linearly as a function of accelerating voltage to 200 kev. It is estimated that about three inelastic interactions for every four carbon atoms is sufficient to cause substantial damage at high resolution; the implications of this result for molecular microscopy are considered. A calibration technique for electron detectors is introduced.