4D-STEM diffraction mapping in electron microscopy using direct electron detectors"

Scanning transmission electron microscopes (STEM) are routinely used for studying materials down to individual atomic columns. Scanning a convergent electron beam across a thinned material yields a rich diffraction pattern in the back focal plane. However, much of this rich information is lost when using standard STEM detectors, which integrate up a large fraction of these diffraction patterns into a single value for each position in the scan. With the recent advances in fast and robust direct electron detectors, it is now possible to acquire these diffraction patterns at 1000+ frames per second. This allows for one diffraction pattern to be acquired for every point in the scan.

This seminar will focus on how this technique works, practical aspects, and applications such as structural characterization using higher order Laue zones and magnetic imaging.