Comments on A new theory for X-ray diffraction
In an article entitled A new theory for X-ray diffraction [Fewster (2014). Acta Cryst. A70, 257–282], hereafter referred to as NTXRD, it is claimed that when X-rays are scattered from a small crystallite, whatever its size and shape, the diffraction pattern will contain enhanced scattering at angles...
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| Format: | Journal article |
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International Union of Crystallography
2018
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| _version_ | 1797060958741331968 |
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| author | Fraser, J Wark, J |
| author_facet | Fraser, J Wark, J |
| author_sort | Fraser, J |
| collection | OXFORD |
| description | In an article entitled A new theory for X-ray diffraction [Fewster (2014). Acta Cryst. A70, 257–282], hereafter referred to as NTXRD, it is claimed that when X-rays are scattered from a small crystallite, whatever its size and shape, the diffraction pattern will contain enhanced scattering at angles of exactly 2B, whatever the orientation of the crystal. It is claimed that in this way scattering from a powder, with randomly oriented crystals, gives rise to Bragg scattering even if the Bragg condition is never satisfied by an individual crystallite. The claims of the theory put forward in NTXRD are examined and they are found to be in error. Whilst for a certain restricted set of shapes of crystals it is possible to obtain some diffraction close to (but not exactly at) the Bragg angle as the crystallite is oriented away from the Bragg condition, this is generally not the case. Furthermore, contrary to the claims made within NTXRD, the recognition of the origin of the type of effects described is not new, and has been known since the earliest days of X-ray diffraction. |
| first_indexed | 2024-03-06T20:24:15Z |
| format | Journal article |
| id | oxford-uuid:2edf5c77-15bd-4cc6-8dea-91c05c15458a |
| institution | University of Oxford |
| last_indexed | 2024-03-06T20:24:15Z |
| publishDate | 2018 |
| publisher | International Union of Crystallography |
| record_format | dspace |
| spelling | oxford-uuid:2edf5c77-15bd-4cc6-8dea-91c05c15458a2022-03-26T12:51:35ZComments on A new theory for X-ray diffractionJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:2edf5c77-15bd-4cc6-8dea-91c05c15458aSymplectic Elements at OxfordInternational Union of Crystallography2018Fraser, JWark, JIn an article entitled A new theory for X-ray diffraction [Fewster (2014). Acta Cryst. A70, 257–282], hereafter referred to as NTXRD, it is claimed that when X-rays are scattered from a small crystallite, whatever its size and shape, the diffraction pattern will contain enhanced scattering at angles of exactly 2B, whatever the orientation of the crystal. It is claimed that in this way scattering from a powder, with randomly oriented crystals, gives rise to Bragg scattering even if the Bragg condition is never satisfied by an individual crystallite. The claims of the theory put forward in NTXRD are examined and they are found to be in error. Whilst for a certain restricted set of shapes of crystals it is possible to obtain some diffraction close to (but not exactly at) the Bragg angle as the crystallite is oriented away from the Bragg condition, this is generally not the case. Furthermore, contrary to the claims made within NTXRD, the recognition of the origin of the type of effects described is not new, and has been known since the earliest days of X-ray diffraction. |
| spellingShingle | Fraser, J Wark, J Comments on A new theory for X-ray diffraction |
| title | Comments on A new theory for X-ray diffraction |
| title_full | Comments on A new theory for X-ray diffraction |
| title_fullStr | Comments on A new theory for X-ray diffraction |
| title_full_unstemmed | Comments on A new theory for X-ray diffraction |
| title_short | Comments on A new theory for X-ray diffraction |
| title_sort | comments on a new theory for x ray diffraction |
| work_keys_str_mv | AT fraserj commentsonanewtheoryforxraydiffraction AT warkj commentsonanewtheoryforxraydiffraction |