The recording of microdiffraction patterns in scanning transmission electron microscopy

Abstract

A VG Scientific HB501 scanning transmission electron microscope has been fitted with a novel system for recording microdiffraction patterns from extremely small volumes of matter (less than 500 atoms) at near-unity detection quantum efficiency and high resolution (0.25 mrad). Electrons are incident upon a 35 mm photographic film which is separated from the ultra-high vacuum of the specimen chamber by a 7.4 mu m thick window of Kapton polyimide foil. Results show that the new system is a considerable improvement on previously available detection techniques.