![]() ![]() In 1936, the first electron microscope was built by Metropolitan-Vickers in the U.K. HistoryĪfter the theory of the wave nature of electrons was developed by Louis DeBroglie in 1925, researchers Knoll and Ruska proposed the idea of an electron microscope. ![]() Magnifications from about 100x up to several hundred thousand times can be achieved in the TEM. Dark-field images are formed from a single diffracted beam and are used to identify all the areas of a particular phase having the same crystalline orientation. An electron diffraction pattern can be generated from a particular area in a bright-field image (such as a particle or grain) by using a selected area aperture. Features in the sample that cause scattering have darker contrast in a bright-field image than those that cause little or no scattering. A bright-field image of the sample can be formed by looking at the straight-through, non-diffracted beam. These diffraction patterns can be used to identify unknown phases in the sample. In crystalline materials, the scattering takes the form of one or more Bragg diffracted beams, which are used to form a transmission diffraction pattern. The sample is illuminated with an almost parallel electron beam, which is scattered by the sample. Apertures are used to select among imaging modes and to select features of interest for electron diffraction work. ![]() The electron microscope consists of an electron gun, or source, and an assembly of magnetic lenses for focusing the electron beam. What is Transmission Electron Microscopy? OverviewĪ TEM (transmission electron microscope) uses a highly energetic electron beam (100 keV - 1 MeV) to image and obtain structural information from thin film samples. Semitracks' Online Training contains short courses and other material useful for any Engineer trying to learn new subjects or brush up on old ones. Are you looking for more information regarding this and other subjects? Look no further than Semitracks' Online Training. ![]()
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