Diffraction, X-ray

Name:
Diffraction, X-ray
Detailed information:
A method of spectroscopic analysis involving the reflection or scattering of x-radiation by the atoms of a substance (lattice) as the rays pass through it. The rays are reflected by the atoms at an angle that is characteristic of the substance, yielding a spectrum that indicates its atomic or molecular structure. The spectra thus obtained are well defined and specific; from them the properties of elements and the structure of both crystalline and amorphous materials can be obtained. For example, unvulcanized rubber gives an amorphous pattern, while vulcanized rubber is crystalline; the cellulose macromolecule has alternating crystalline and amorphous areas. X-ray diffraction was one of the earliest and most successful methods of instrumental analysis; developed by Bragg and van Laue early in this century, it was used with dramatic effect by Moseley (1912) in establishing the location of several elements in the periodic system.See Lattice; Crystal; X-radiation.