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Figure 16
Illustration of fitting Ewald sphere sections, of radius cos(β)/λ, to pairs of reciprocal-lattice points. (a) Three observed peaks with radii RA, RB and RC, and specimen tilts between 0 and 25°, are considered. The best indexings for β = 0° and β = 25° are shown. The indexing of both pairs of radii share the common reciprocal lattice point B. (b) A close-up around reciprocal lattice point B. In both indexing cases, the Ewald sphere never intercepts point B for the range of β values present (0°, 25°). Moreover, indexing is not possible for β larger than particular values as the Ewald sphere is not within the accepted tolerance radius T of the reciprocal lattice point B. As a result, only the regions shaded grey can accrue diffraction for the two indexing scenarios, leading to a fragmented intensity distribution about the reciprocal lattice point B in the merged data.

IUCrJ
Volume 4| Part 6| November 2017| Pages 795-811
ISSN: 2052-2525
https://doi.org/10.1107/S2052252517014324