Selected techniques in diamond anvil cell crystallography: centring samples using X-ray transmission and rocking powder samples to improve X-ray diffraction image quality
The distinct X‐ray transmission profile obtained by scanning a sample in a diamond anvil cell across a collimated X‐ray beam is used to monitor sample displacement brought about by rotation. This measured displacement can in turn be used to calculate, and subsequently correct, the sample position wi...
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Published in | Journal of synchrotron radiation Vol. 16; no. 1; pp. 83 - 96 |
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Main Authors | , |
Format | Journal Article |
Language | English |
Published |
5 Abbey Square, Chester, Cheshire CH1 2HU, England
International Union of Crystallography
01.01.2009
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Subjects | |
Online Access | Get full text |
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Summary: | The distinct X‐ray transmission profile obtained by scanning a sample in a diamond anvil cell across a collimated X‐ray beam is used to monitor sample displacement brought about by rotation. This measured displacement can in turn be used to calculate, and subsequently correct, the sample position with respect to a centre of rotation. This centring method differs from others also based on transmission in that it does not require a 180° sample rotation, nor does it require prior positioning of the rotation axis in the path of the X‐ray beam. After a full description of the method, an example is presented together with an extended record of use to evaluate the method in a practical setting. The practice and benefits of rocking polycrystalline samples during X‐ray exposure have also been quantitatively examined. Changing the orientation of the sample grains with respect to the incident beam yields the expected result of a more homogeneous intensity distribution along Debye rings. Interestingly, by limiting the amount of time large grains assume a particular orientation, rocking brings about the added effect of significantly reducing detector saturation. Sample rocking yields more reliable relative intensities, a more appropriate line shape and narrower line width. Data are presented for a calibration standard at ambient pressure as well as a research sample at high pressure. |
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Bibliography: | istex:0B665EF5CF8B57B8D2728C4ED73E8613269E6922 ark:/67375/WNG-LVND1998-4 ArticleID:JSYIE5024 ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2 |
ISSN: | 1600-5775 0909-0495 1600-5775 |
DOI: | 10.1107/S0909049508030859 |