Electron Diffraction

Electyron Diffraction refers to the wave nature of electrons. However, a from of technical or practical point of view, it may be regarded as a technique used to study matter by firing electrons at a sample and observing the resulting interference pattern. This phenomenon is commonly known as the wave particle duality, in which it states that the behavior of a particle of matter (in this case the incident electron) can be described by a wave. For this reason an electron can be regarded as a wave, like sound or water waves. This technique is similar to X-ray and neutron diffraction.

Electron diffraction is most frequently used in the solid state physics and chemistry to study the crystal structure of solids. Experiments are usually performed in the transmission electron microscope (TEM), or a scanning electron microscope (SEM) as electron back scatter diffraction. In these instruments electrons are accelerated by electrostatic potential in order to gain the desired energy and determine their wavelength before they interact with the sample to be studied.

Electron Diffraction in Materials Science

Electron diffraction is an very important technique for crystallographic characterization, a valuable complementary tool to powder and single crystal X-ray diffraction.

Applications include phase identification and precision determination of suitable structural details for crystals in the micrometer to nanometer size range.

Electron Diffraction with the PDF-4+ Database

• The PDF-4+ database can be used to generate two types of electron diffraction patterns for all PDF entries with atomic coordinates:
  1.   Transmission electron spot patterns
  2.   Electron back scattering patterns
• To illustrate electron diffraction pattern generation with the PDF-4+ database, Iron (Fe, face centered
• cubic (FCC), space group Fm-3m) will be used as an example.
• The PDF-4+ database cannot perform search-match procedures directly on digital electron diffraction patterns, they must first be indexed to obtain a d-spacing-intensity (d/I) list. Search-match procedures can then be performed using SIeve+.
• Electron diffraction patterns generated by the PDF-4+ database do not account for intensity variation due to either sample or instrumental effects.