The original electron diffraction experiments were perfomed by Davidsson and Germer using reflection, what is now called Low-energy electron diffraction, and in transmission by Thompson and Reid. While useful diffraction information could be obtined, for many years imaging in transmission electron microscopes was only at modest resolutions; it was not until much later that Bauer demonstrated imaging at low energies. Therefore most of the earliest electron crystallography used transmission diffraction, particularly exploiting the lens configurations developed by ... which emabled selected area diffraction to be performed. Despite these limitations there were signifcant works, for instance ...
Towards the end on the 1970s and the early 1980s transmission electron microscopes achieved a good enough resolution that they could start to be used to image materials at the atomic scale. Companion to this was the development of fast numerical methods for both calculating the diffraction as electrons traversed samples, and also the effect of imaging aberrations such as defocus and spherical aberration. This led to ...
At about the same time the Convergent-beam electron diffraction technique was developed. This played a major role in electron crystallography and general structure determination as it was possible to determine the presence (or absence) of symmetry elements such as screw axes and glide planes. Both of these are hard to unconditionally determine using x-ray diffraction methods. Some of the successes were for ...
The early 1980s ushered in extensive work where imaging, conventional diffraction and CBED techniques were combined with image simulations to analyze atomic structures. Almost all of this work was mainly to find the approximate positions of atoms, which were then refined (if desired) using X-ray diffraction techniques. Once the space-group and the approximate positions were determined, it was much easier to obtain accurate information.