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![[Figure 2]](he4557fig2mag.jpg)
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Figure 2
Twinned CD9EC2 crystal. (a) Reciprocal space reconstructions, hk0, hk2 and hk4. The lower panels are zoomed in at the area of the yellow box, where Bragg reflections originating from lattice 1 and 2 are coloured white and cyan, respectively. In slice hk2, streaks along a* + b* are evident. All slices hk(l = 4n) are ordered and the spots indexed by the two matrices nearly overlap, while in slices hk(l = 4n + 2) they have maximum separation. (b) Green and gold structures represent the two twin domains in the crystal. The second domain is rotated by 180° around a* + b* with respect to the first. The twin interface is the plane in the middle with base vectors c and a − b for either lattice. In the figure, molecules of the two domains are overlayed on this layer. The 180° twin rotation applied to domain 1 causes chains A and C of the molecules in domain 1 (green) to superimpose on chains B and D of domain 2 (gold), respectively. Starting from the interface the 4th layers (between the blue lines) in the two domains are the same and form an ordered array. A super cell (red) can be constructed with transformation matrix (1,−1,0/0,0,1/−2,−2,1) on which the two twin lattices overlap. The consequence is that in reciprocal space reflections of the twin lattices overlap for every l = 4n. |
![[Figure 2]](he4557fig2.jpg)
 | IUCrDATA |
ISSN: 2414-3146
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