 | Acta Crystallographica Section A Acta Crystallographica Section A FOUNDATIONS AND ADVANCES |
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![[Figure 3]](lk5041fig3mag.jpg)
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Figure 3
An ensemble of CBED patterns showing magnified components of a WP (a) and a ±DP pair (b) and (c). The WP (a) consists of the BP, which is the central beam, 000, and the six reflections surrounding the central beam. The incident electron beam in (a) is oriented along a zone axis. The HOLZ deficiency lines in 000 show that only a single mirror is present in the 3D crystal structure parallel to this zone axis. This is marked by the white line in (a). See Fig. 5 ![[link]](../../../../../../logos/arrows/a_arr.gif) for a wider field of view of this on-axis pattern, showing more of the ZOLZ. Part (b) shows the 000 and +G discs where the Bragg condition for the latter is satisfied. Part (c) shows the 000 and −G discs where the Bragg condition for the latter is satisfied. Parts (b) and (c) together constitute the ±DP pair. Because the scattering vectors for +G and −G constitute a Friedel pair, the equivalence of the intensity distribution in both of these discs shows the presence of an inversion centre in the structure projected along this zone axis. Furthermore, mirror symmetry in the intensity distribution within ±G (marked by the white lines in both cases) is consistent with the determination that there is a 3D mirror in the crystal structure along this zone axis. |
![[Figure 3]](lk5041fig3.jpg)
| FOUNDATIONS ADVANCES |
ISSN: 2053-2733
