Ratings of New Films for the High-Voltage Electron Microscope and the Radiation Damage Incurred in Taking Typical Biological Electron Micrographs

Radiation damage to biological specimens being examined in the electron microscope inevitably restricts the amount of information that can be gathered. This problem is especially severe in the high-voltage electron microscope (HVEM), where the relatively low sensitivities of existing photographic materials entail inordinately long exposures to specimens to the beam that cause enhanced radiation damage, in spite of early hopes that this instrument would alleviate the radiation-damage problem. We have reported studies of the sensitivities and resolutions of commercial and experimental photographic materials for use with 1-MeV electrons. In the present study, we have chosen certain photographic materials as representing typical films used for electron microscopy or as possessing a favorable combination of sensitivity and resolution for biological electron microscopy, and we have followed the course of impairment of image quality as a selected area of a typical specimen is subjected to ever larger radiation doses.