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An X-ray diffraction pattern of a crystallized enzyme. The pattern of spots (reflections) and the relative strength of each spot (intensities) can be used to determine the structure of the enzyme. The relative intensities of the reflections provides information to determine the arrangement of molecules within the crystal in atomic detail.
X-ray diffraction is a generic term for phenomena associated with changes in the direction of X-ray beams due to interactions with the electrons around atoms. It occurs due to elastic scattering , when there is no change in the energy of the waves.
This is directly related to the fact that information is lost by the collapse of the 3D space onto a 1D axis. Nevertheless, powder X-ray diffraction is a powerful and useful technique in its own right. It is mostly used to characterize and identify phases, and to refine details of an already known structure, rather than solving unknown structures.
X-ray diffraction (XRD) is still the most used method for structural analysis of chemical compounds. Yet, with increasing detail on the relation of K β {\displaystyle K_{\beta }} -line spectra and the surrounding chemical environment of the ionized metal atom, measurements of the so-called valence-to-core (V2C) energy region become ...
XRD may refer to: X-ray diffraction , used to study the structure, composition, and physical properties of materials Extensible Resource Descriptor , an XML format for discovery of metadata about a web resource
In principle the scattering factor () can be used to determine the scattering from a perfect crystal; in the simple case when the basis is a single atom at the origin (and again neglecting all thermal motion, so that there is no need for averaging) all the atoms have identical environments.
X-ray diffraction topography is one variant of X-ray imaging, making use of diffraction contrast rather than absorption contrast which is usually used in radiography and computed tomography (CT). Topography is exploited to a lesser extent with neutrons , and is the same concept as dark field imaging in an electron microscope .
André Authier: Dynamical theory of X-ray diffraction. IUCr monographs on crystallography, no. 11. Oxford University Press (1st edition 2001/ 2nd edition 2003). ISBN 0-19-852892-2. R. W. James: The Optical Principles of the Diffraction of X-rays. Bell., 1948. M. von Laue: Röntgenstrahlinterferenzen. Akademische Verlagsanstalt, 1960 (German).