Chapter

Practical aspects of data processing

Alexander Blake

in Crystal Structure Analysis

Second edition

Published in print June 2009 | ISBN: 9780199219469
Published online September 2009 | e-ISBN: 9780191722516 | DOI: http://dx.doi.org/10.1093/acprof:oso/9780199219469.003.0007

Series: International Union of Crystallography Texts on Crystallography

Practical aspects of data processing

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An area detector diffractometer provides a large set of raw image frames, from which integrated intensities must be extracted. Necessary prior knowledge includes the unit cell and crystal orientation, of which there may be more than one if the crystal is twinned or otherwise non-single. Data integration involves the allocation of individual frame pixels to reflections and background, often with some kind of profile fitting. Corrections are made for effects such as absorption, and the results consist essentially of a list of reflection indices with corresponding intensities and standard uncertainties. Other ouput includes a range of diagnostics, statistical analyses, and measures of data quality and completeness. This chapter describes a typical experiment and gives examples of problems that may arise and methods to tackle them.

Keywords: integration; data corrections; profile fitting; twinning; data completeness; diagnostics

Chapter.  3165 words.  Illustrated.

Subjects: Crystallography

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