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The correction of reflection intensities for incomplete absorption of high‐energy X‐rays in the CCD phosphor
Author(s) -
Wu G.,
Rodrigues B. L.,
Coppens P.
Publication year - 2002
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889802005770
Subject(s) - phosphor , optics , synchrotron radiation , absorption (acoustics) , multipole expansion , reflection (computer programming) , wavelength , physics , synchrotron , radiation , total internal reflection , materials science , optoelectronics , quantum mechanics , computer science , programming language
It is shown that incomplete absorption of the X‐ray beam in the phosphor of an area detector causes an incident‐angle dependence of the recorded X‐ray intensities. An energy scan of a SMART‐6000 CCD (charge‐coupled device) phosphor using synchrotron radiation shows the correction to be of importance above about 17 keV. Intensities of single reflections, each collected several times at different angles of incidence on the phosphor surface, show a pronounced angle‐dependence at shorter wavelengths. Both conventional structural refinement and multipole charge density studies confirm that an oblique‐incidence correction leads to improved quality of the results. Atomic displacement parameters will be systematically biased when the correction is not applied. For a λ = 0.394 Å data set, neglecting the correction gives rise to artifacts in the deformation density maps that are likely to lead to misinterpretation of the experimental results.