$tem diffraction pattern analysis$

The transformation from the real space to the reciprocal space is mathematically given by the Fourier transform. The space where the diffraction pattern forms is called reciprocal space, while the space at the image plane or at a specimen is called real space. If the transmitted and the diffracted beams interfere on the image plane, a magnified image of the sample can be observed. The use of electromagnetic lenses allows diffracted electrons to be focused into a regular arrangement of diffraction spots that are projected and recorded as the electron diffraction pattern. The diffracted waves are recombined to form an image on the image plane. Diffracted waves scattered by the atomic potential form diffraction spots on the back focal plane after being focused with the objective lens. The main principles of electron microscopy can be understood by use of optical ray diagrams, as shown in Fig. As the result of numerous advances in optics and microscope design, modern TEMs are capable of a resolution of 1.65 Å for 300 kV (and below 1 Å for 1000 kV) electron energy-loss combined with chemical analysis (through x-ray energy and electron-loss energy spectroscopy) and a bright coherent field emission source of electrons. The elektronograf is very similar to a modern transmission electron microscope (TEM), in which the scattered transmitted beams can be also recombined to form an image. In the elektronograf, magnetic lenses were used to focus 50 keV to 100 keV electrons to obtain diffraction with scattering angles up to 3° to 5° and numerous structures of organic and inorganic substances were solved. Vainshtein and his colleagues as early as the 1940s. The use of electron diffraction to solve crystallographic problems was pioneered in the Soviet Union by B.

$tem diffraction pattern analysis$

Tem diffraction pattern analysis