X

X-ray diffraction (or X-ray crystallography) is the determination of crystal structure by analysis of the diffraction pattern of X-rays caused by a crystal in their path. In the technique, the intensity of the diffraction at each orientation of a single crystal is measured, interpreted in terms of structure factors, and then used to construct the electron density distribution in a unit cell by Fourier synthesis. Absolute configurations can be determined by making use of the Bijvoet method. Powder samples give characteristic patterns and can be used to analyse the composition of samples and to determine the symmetry and dimensions of unit cells.