Kikuchi line

Kikuchi lines are characteristic lines are formed in the electron diffraction by transmission electron diffraction or the backscattered electrons in scanning electron microscopes.

Your name goes back to their description by Seishi Kikuchi 1928.

Formation

The Kikuchi lines caused by multiple scattering of the electrons. If a material is bombarded with electrons, these have a defined kinetic energy. Now it may happen that the electrons are scattered more than once in the sample, but continue to fly after the first scattering is isotropic and with random wave vector and scattered again. The energy loss in the first dispersion has to but small compared to the electron energy to be. Very important is the double scattering. Through the first inelastic collision, the electron undergoes a minor distraction to the incident direction. The elastically scattered electrons are then diffracted by lattice planes.

On the basis of a crystal lattice, this can be by means of the kinematic scattering theory easy to explain, even though this is a dynamic phenomenon:

After the Laue condition is true. In contrast to the Ewald construction of the vector is plotted on a grid center. Thereby to form a ball at that point. Each intersection of this sphere with the Brillouin zone boundary results in a reflex. While in the Ewald construction so individual points to be made and so the diffraction image is point-like, here intersect ball and surface (depending on the Brillouin zone ) and thus it creates a line pattern.

Application

The Kikuchi lines can be observed as well as in electron backscattering for electron transmission. A common application is to be found in connection with the RHEED (of English. Reflection high energy electron diffraction ). Here, the crystal can be analyzed with the method described therein as well as using the Kikuchi lines, which are also observed. A further application can be found in the EBSD method ( ENGL. Electron backscatter diffraction ), in which the Kikuchi lines are recorded in the scanning electron back-scattered ( at the appropriate geometry) electrons, in order to determine the crystal structure and orientation.