<P> Electron diffraction refers to the wave nature of electrons . However, from a 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 wave--particle duality, which states that a particle of matter (in this case the incident electron) can be described as a wave . For this reason, an electron can be regarded as a wave much like sound or water waves . This technique is similar to X-ray and neutron diffraction . </P> <P> Electron diffraction is most frequently used in solid state physics and chemistry to study the crystal structure of solids . Experiments are usually performed in a transmission electron microscope (TEM), or a scanning electron microscope (SEM) as electron backscatter diffraction . In these instruments, electrons are accelerated by an electrostatic potential in order to gain the desired energy and determine their wavelength before they interact with the sample to be studied . </P> <P> The periodic structure of a crystalline solid acts as a diffraction grating, scattering the electrons in a predictable manner . Working back from the observed diffraction pattern, it may be possible to deduce the structure of the crystal producing the diffraction pattern . However, the technique is limited by phase problem . </P> <P> Apart from the study of crystals i.e. electron crystallography, electron diffraction is also a useful technique to study the short range order of amorphous solids, and the geometry of gaseous molecules . </P>

Why electrons are allowed to fall on a crystal plate for diffraction
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