I have a TEM diffracting pattern of a selected sample area H

I have a TEM diffracting pattern of a selected sample area. How can I get the image of this area based on the diffracting pattern data.(Not do the TEM experiment one more time.) How to do it and what is the mechanism?

Solution

Selected area (electron) diffraction (abbreviated as SAD or SAED), is a crystallographic experimental technique that can be performed inside a transmission electron microscope (TEM).

In a TEM, a thin crystalline specimen is subjected to a parallel beam of high-energy electrons. As TEM specimens are typically ~100 nm thick, and the electrons typically have an energy of 100–400 kiloelectron volts, the electrons pass through the sample easily. In this case, electrons are treated as wave-like, rather than particle-like (see wave-particle duality). Because the wavelength of high-energy electrons is a few thousandths of a nanometer,^[1] and the spacing between atoms in a solid is about a hundred times larger, the atoms act as a diffraction grating to the electrons, which are diffracted. That is, some fraction of them will be scattered to particular angles, determined by the crystal structure of the sample, while others continue to pass through the sample without deflection.

As a result, the image on the screen of the TEM will be a series of spots—the selected area diffraction pattern, SADP, each spot corresponding to a satisfied diffraction condition of the sample\'s crystal structure. If the sample is tilted, the same crystal will stay under illumination, but different diffraction conditions will be activated, and different diffraction spots will appear or disappear.