Difference Between X Ray Diffraction and Electron Diffraction

The key difference between X ray diffraction and electron diffraction is that X ray diffraction involves the diffraction of an incident beam of X rays into different directions whereas electron diffraction involves the interference of an electron beam.

Both X ray diffraction and electron diffraction are analytical techniques that we can use to study matter. Another such technique is neutron diffraction. These techniques reveal the crystal structures of matter. Therefore the applications of these techniques are in solid-state physics and chemistry.

CONTENTS

1. Overview and Key Difference
2. What is X Ray Diffraction
3. What is Electron Diffraction
4. Side by Side Comparison – X Ray Diffraction vs Electron Diffraction in Tabular Form
5. Summary

What is X Ray Diffraction?

X ray diffraction or X ray crystallography is an analytical technique that we use to determine the structure of crystals. Hence, the theory behind the technique involves the diffraction of an incident X ray beam into different directions. In brief, by measuring the angles and intensities of the diffracted beams, we can determine the 3D picture of the electron density within that crystal. Consequently, the electron densities give the positions of atoms in the crystal structure. Furthermore, we can determine the chemical bonds and various other information as well.

Crystals have regularly arranged atoms. X rays are waves of electromagnetic radiation. Therefore, the atoms in the crystal can scatter the X-ray beams through the electrons of the atoms. As a result, X rays striking the electrons produce secondary waves (spherical waves) emerge from the electron. We call this process as “elastic scattering” and electron acts as the scatterer. However, these waves cancel one another via destructive interference.

What is Electron Diffraction?

Electron diffraction is an analytical technique that we use to study the matter. Hence, the theory behind this technique involves the firing of electrons at a sample to observe the interference patterns of the electron beam. The term interference refers to the formation of a resultant wave from two waves that have greater, lower or equal amplitude. Usually, we perform this experiment in a transmission electron microscope (TEM) or in a scanning electron microscope (SEM). These instruments use an accelerated electron beam (accelerated by an electrostatic potential).

Crystalline solids have a periodic structure of atoms. This periodic structure acts as a diffraction grating (splits and diffracts the electron beam into several beams that travel in different directions). There, the scattering of electrons occurs in a predictable manner. The pattern of diffraction gives us details to predict the structure of the crystal. However, this technique has a great limitation by phase problem (the problem of loss of information concerning the phase that can occur when making a physical measurement).

What is the Difference between X Ray Diffraction and Electron Diffraction?

X ray diffraction and electron diffraction are important analytical techniques that we can use to determine the crystal structure of crystalline solids. The key difference between X ray diffraction and electron diffraction is that X ray diffraction involves the diffraction of an incident beam of X rays into different directions whereas electron diffraction involves the interference of an electron beam.

Moreover, X ray diffraction uses a beam of X rays while electron diffraction uses a beam of electrons. As another important difference between X ray and electron diffractions, electron diffraction is limited by phase problem while it has no considerable effect on X ray diffraction. More details are shown in the infographic on difference between X ray diffraction and electron diffraction.

Summary – X Ray Diffraction vs Electron Diffraction

Both X ray diffraction and electron diffraction are techniques that we can use to determine the structure of crystals. The key difference between X ray diffraction and electron diffraction is that X ray diffraction involves the diffraction of an incident beam of X rays into different directions whereas electron diffraction involves the interference of an electron beam.

Reference:

1. “X-Ray Crystallography.” Wikipedia, Wikimedia Foundation, 7 Nov. 2018. Available here 
2. “Electron Diffraction.” Wikipedia, Wikimedia Foundation, 12 July 2018. Available here 

Image Courtesy:

1.”Freezed XRD”By Kaspar Kallip – Own work, (CC BY-SA 4.0) via Commons Wikimedia  
2.”DifraccionElectronesMET”By Oysteinp at the English language Wikipedia, (CC BY-SA 3.0) via Commons Wikimedia