5. The contribution of X-ray and neutron diffraction

5.1 Principle of X-ray and neutron diffraction

Every crystallized compound has its own diffractogram, like a fingerprint. This diffractogram is obtained after X-rays interact with matter. The wavelength of X-rays is of the order of an angstrom, 10 ^–10 m. Matter, being ordered, plays the same role as a grating in optics. If we call d the distance between the lattice planes of the structure, θ the angle of incidence between the direct beam and the family of lattice planes spaced by d and λ the wavelength of the incident radiation, diffraction will only occur if Bragg's law is verified: