Electron Nanodiffraction: Progress and Prospects

Electron diffraction patterns may be obtained from regions 1 nm or less in diameter when a field-emission gun is used to form a very small bright source, as is usual in scanning transmission electron microscopy (STEM) instruments. Because the beam incident on the specimen can be assumed to be completely coherent, interference fine structure is visible in the patterns and provides the basis for deriving more detailed information on the specimen structure. For large angles of incident beam convergence, the diffraction patterns can be interpreted as in-line electron holograms. It has been proposed that the nanodiffraction patterns from each pixel of a STEM image should be combined to greatly enhance the image resolution.