![]() Precession electron diffraction (PED) is a unique technique to collect ED patterns. Ultramicroscopy 2007, 107, 483–494, with permission from the International Union of Crystallography, copyright 2007. (C) Simulated diffraction pattern, using the kinematical approximation. Electron diffraction patterns of uvarovite, Ca 3Cr 2(SiO 4) 3, with precession (A) off and (B) on. In order to determine the unit cell parameters of an unknown crystal, it is necessary to tilt the crystal and collect SAED patterns from different orientations.įig. 3. Thus, SAED is mostly used for analyzing known materials. Therefore, it is difficult to obtain 3D information from a single SAED pattern. Because of the short wavelength of electrons, the Ewald sphere is almost flat when cutting through the reciprocal lattice of a crystal. An example SAED pattern is shown in Fig. 3A. Depending on the type of sample, the SAED pattern can contain sharp spots from single crystal, ring patterns from nanocrystalline powders, or diffused ring patterns from amorphous samples. When the intermediate lens is focused on the back focal plane, an SAED pattern is displayed. A selected area aperture, which is located at the imaging plane below the sample, is typically used to limit the area used for obtaining an SAED pattern. Selected area electron diffraction (SAED) is one of the most common techniques for acquiring two-dimensional (2D) electron diffraction patterns. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |