Extinction-free measurements in crystallography

ABSTRACT OVER the past fifty or more years extinction has remained a major experimental problem in crystallography1–3. Many strategies have been devised to reduce its magnitude for the

accurate determination of physically-significant structure factors (_F_). Its elimination, as a practical possibility, has appeared remote because extinction is a concomitant of the

production of diffraction intensity in the standard techniques. Phenomenologically, extinction is a manifestation of multiple diffraction (see ref. 4), and this being so, an obvious

conclusion is that the experimental disposition to be sought is one where the recorded intensity must arise solely from single-scattering events5–7. Then, by definition, the diffracted beam

is not ‘extinguished’ and simple kinematical theory is applicable. Starting with the design of a ‘defocusing’ X-ray monochromator8, I have been investigating the intensity of asymmetric

reflections from extended-face crystals over the regions of both positive and negative asymmetry, first with an abraded surface9 and then with an optically flat one. The results from this

latter study, with an extrapolation of the work of Hirsch and Ramachandran5, show that it is feasible to establish values of integrated intensity which involve only single-scattering events.

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support SIMILAR CONTENT BEING VIEWED BY OTHERS EXPERIMENTAL PHASING OPPORTUNITIES FOR MACROMOLECULAR CRYSTALLOGRAPHY AT VERY LONG WAVELENGTHS Article Open access 12 October 2023 X-RAY

DIFFRACTION UNDER GRAZING INCIDENCE CONDITIONS Article 29 February 2024 A QUANTUM CRYSTALLOGRAPHIC PROTOCOL FOR GENERAL USE Article Open access 19 April 2025 REFERENCES * Bragg, W. L.,

James, R. W., and Bosanquet, C. H., _Phil. Mag._, 41, 309–337 (1921); 42, 1–17 (1921). Article  CAS  Google Scholar  * Conference Report, _Acta Crystallogr._, A 25, 1–276 (1969). *

I.U.Cr.-Aust. Acad. Sci., _Diffraction Studies of Real Atoms and Real Crystals_, Topic I, 11–127 (Australian Academy of Science, Canberra, 1974). * Darwin, C. G., _Phil. Mag._, 43, 800–829

(1922). Article  CAS  Google Scholar  * Hirsch, P. B., and Ramachandran, G. N., _Acta Crystallogr._, 3, 187–194 (1950). Article  CAS  Google Scholar  * Gay, P., _Acta Crystallogr._, 5,

525–530 (1952). Article  Google Scholar  * Evans, R. C., Hirsch, P. B., and Kellar, J. N., _Acta Crystallogr._, 1, 124–129 (1948). Article  CAS  Google Scholar  * Mathieson, A. McL., _J.

appl. Crystallogr._, 8, 571 (1975). Article  Google Scholar  * Mathieson, A. McL., _Acta Crystallogr._, A 31, 769–774 (1975). Article  Google Scholar  * James, R. W., _The Optical Principles

of the Diffraction of X-Rays_, 279 (Bell, London, 1948). Google Scholar  * Fankuchen, I., _Nature_, 139, 193–194 (1937). Article  ADS  CAS  Google Scholar  * Bragg, W. H., _Phil. Mag._, 27,

881–899 (1914) (reproduced in _Acta Crystallogr._, A 25, 3–11 (1969). Google Scholar  Download references AUTHOR INFORMATION AUTHORS AND AFFILIATIONS * CSIRO Division of Chemical Physics,

PO Box 160, Clayton, Victoria, Australia, 3168 A. MCL. MATHIESON Authors * A. MCL. MATHIESON View author publications You can also search for this author inPubMed Google Scholar RIGHTS AND

PERMISSIONS Reprints and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE MATHIESON, A. Extinction-free measurements in crystallography. _Nature_ 261, 306–308 (1976).

https://doi.org/10.1038/261306a0 Download citation * Received: 08 March 1976 * Accepted: 07 April 1976 * Published: 01 May 1976 * Issue Date: 27 May 1976 * DOI:

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