Energy Selecting Microscope

Abstract

A new instrument called “Energy Selecting Microscope” has been completed, by means of which electron microscope images and diffraction patterns formed by mono-energetic electrons of any pre-selected energy can be obtained. The energy of electrons forming an image or pattern is analysed by a Möllenstedt type analyser, and the electrons within a certain energy range are selected by a slit placed on the plane of the energy spectrum. To obtain the entire image of the specimen, the images on the entrance slit of the analyser and on the final screen are scanned perpendicularly to the slit by properly synchronized saw-tooth voltages. The energy resolution of the selected-energy image is approximately 1 eV at 50 kV acceleration. In the case of amorphous specimens such as carbon particles, the characteristic-loss electron image looked similar to the ordinary dark field image, while Fresnel fringes did not appear in the loss electron images. In the case of crystalline specimens the extinction contours and dislocations were clearly observed in the characteristic-loss electron images. This observation indicates that the characteristic-loss electrons produced a diffraction contrast similar to that of no-loss electrons.