May 3 2014
Bragg’s law describes the angles for the coherent and incoherent scattering from a crystal lattice. As per Bragg’s law, when X-rays are scattered from a crystal lattice, the peaks of scattered intensity correspond to the following conditions:
- The angle of incidence is equal to the angle of scattering
- The difference in path length is an integer value of the number of wavelengths
Bragg’s law gives the condition for the maximum intensity and the details about the crystal lattice. In conditions where the crystal structure is known, the wavelength of the X-rays incident on the crystal can be calculated using Bragg’s law.
Bragg’s diffraction was first proposed by William Lawrence Bragg and William Henry Bragg, in the year 1913, during their experiments on crystalline solids. Bragg’s diffraction occurs when electromagnetic radiation, or subatomic particle, waves have wavelengths that are comparable to atomic spacing in a crystal lattice.
The penetrating X-ray travels down the internal layer, gets reflected, and travels back through the same distance as the back of the surface. The distance traversed by the wave is dependent on the distance between the layers of the lattice and the angle of incidence of the X-ray.
Bragg’s equation is given below:
2dsinθ = nλ
where n is the integer, λ is the wavelength, and θ is the angle of scattering.
Souces and Further Reading