With the advances in preparing biological materials in a thin and highly
ordered form, and in maintaining them hydrated under vacuum, electron
crystallography has become an important tool for biological structure
investigation at high resolution (1,2). However, the electron radiation
damage would limit the capability of recording reflections with low
intensities in an electron diffraction pattern. It has been demonstrated
that the use of a low temperature stage can reduce the radiation damage
effect and that one can expose the specimen with a higher dose in order to
increase the signal contrast (3). A further improvement can be made by
selecting a proper photographic emulsion. The primary factors in evaluating
the suitability of photographic emulsion for recording low dose diffraction
patterns are speed, fog level, electron response at low electron exposure,
linearity, and usable range of exposure. We have compared these factors with
three photographic emulsions including Kodak electron microscopic plate
(EMP), Industrex AA x-ray film (AA x-ray) and Kodak nuclear track film
(NTB3).
