Bragg diffraction

Bragg diffraction, also known as Bragg scattering, is a phenomenon that occurs when waves—such as X-rays, neutrons, or light waves—are scattered in a particular direction off the planes of atoms in a crystal, resulting in a constructive interference due to a path difference between the waves. This effect was first proposed by William Henry Bragg and his son William Lawrence Bragg in 1913 to explain why the crystal structure of salts could diffract X-ray beams in specific directions. The Braggs were awarded the Nobel Prize in Physics in 1915 for their work, which laid the foundation for the field of X-ray crystallography.

The condition for Bragg diffraction is given by the Bragg's law, which can be expressed as: \[ n\lambda = 2d\sin\theta \] where:

• \(n\) is an integer known as the order of the diffracted beam,
• \(\lambda\) is the wavelength of the incident wave,
• \(d\) is the distance between the crystal planes, and
• \(\theta\) is the angle of incidence that satisfies the condition for constructive interference.

Bragg diffraction is a powerful tool in the analysis of crystal structures. It is widely used in physics, chemistry, biology, and materials science to determine the atomic and molecular structure of crystals. The technique involves directing X-ray beams at a crystal, measuring the angles and intensities of the diffracted beams, and using this information to deduce the positions of atoms within the crystal.

The applications of Bragg diffraction extend beyond simple structure determination. It is also used in the study of phase transitions, the measurement of strains in materials, and the characterization of thin films and nanomaterials. Advanced techniques, such as neutron diffraction and electron diffraction, employ the same principles to investigate properties of materials that are not accessible with X-rays.