 | Acta Crystallographica Section A Acta Crystallographica Section A FOUNDATIONS AND ADVANCES |
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![[Figure 13]](vk5022fig13mag.jpg)
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Figure 13
High-resolution diffraction space maps of different diffraction peaks from a high-quality (a) and poor-quality (b) lysozyme crystal each of a few hundred micrometres (crystals courtesy of E. H. Snell in 1996). These maps obtained with the multiple-crystal diffractometer, described in Fewster (1989  , 2015), can be used to estimate the crystal quality from the FWHM in Ω to calculate an approximate intensity distribution (Fig. 14). The estimation will make assumptions regarding the number and therefore dimensions of the regions of similar curvature; however, as discussed in the text, if the regions scatter with a coherent relationship the size broadening effects will have less impact on the FWHM and the curvature will dominate, i.e. the number of regions in the calculation is not critical. With this assumption, the crystal plane curvature is equivalent to 3.2° in (b) and 0.01° in (a). The inclined diffraction spot in (b) results from curvature of the crystal planes normal to the figure resulting in a projection, revealed by three-dimensional reciprocal-space mapping (Fewster, 2015). This tilting in two dimensions also makes this map projection unreliable for obtaining precise 2θ values. |
![[Figure 13]](vk5022fig13.jpg)
| FOUNDATIONS ADVANCES |
ISSN: 2053-2733
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