FIGURE 10.

(A) Let us consider particles piling up in columns which are organized on a hexagonal lattice with an intercolumn distance a_H. (B) On the equator, the diffraction diagram displays Bragg reflections characterizing the column organization. Layer lines normal to the meridian are also visible, which characterize the particle distribution along the columns. In the case of a periodic distribution along the columns of period c = 2 h, these layer lines are located at distances q_| = π/h, 2π/h, 3π/h, and 4π/h, from the equator. (C) The calculation of the scattering intensity along these four layer lines show that those at 2π/h and 4π/h are the most intense. (D) In the case of a disorientated sample, these intense layer lines yield scattering rings broader than the instrumental resolution, the broadening decreasing with the diffraction order. In contrast, the diffraction rings characterizing the intercolumn order have the resolution width if this order has an infinite extension.