view article
Figure 6
Four-dimensionally indexed diffraction pattern of a hypothetical modulated structure (a). The vectors a* and c* which define the basic cell are derived from the positions of the main reflections. The additional vector q, reaching from the main reflection to the satellite, can be expressed in fractions of those basic vectors: in the present example q = 0.125·a* + 0·b* + 0·c*. Note that by introducing only one additional vector it is possible to uniquely index all reflections with four integer numbers. The fourth index also reveals the satellite order: the marked satellite reflection at the top is the minus second-order satellite reflection of the main reflection 3 0 2. (b) Diffraction pattern generated by a one-dimensionally modulated crystal. The reflections (green circles) along as4* (defined by the linear combination of [{\bf e}_4^*] and q in the plane of the paper, see §1.2.4[link]) are projected as satellite reflections (grey circles) onto R*, the reciprocal three-dimensional space in which the reciprocal lattice vectors a*, b* and c* (not shown) are defined (see also supplementary material Fig. S1 ).

Journal logoSTRUCTURAL SCIENCE
CRYSTAL ENGINEERING
MATERIALS
ISSN: 2052-5206
Volume 65| Part 3| May 2009| Pages 249-268
doi:10.1107/S0108768109015614
Follow Acta Cryst. B
Sign up for e-alerts
E-alerts
Follow Acta Cryst. on Twitter
Twitter
Follow us on facebook
Facebook
Sign up for RSS feeds
RSS