Kossel Images as Direct Manifestations of the Gap Structure of the Dispersion Surface for Colloidal Crystals

Laser diffraction experiments were made for colloidal crystals of highly charged polyballs in semidilute aqueous solutions at low ionic strength. Fine structures with line uncrossings and splittings were observed at otherwise intersecting points of Kossel rings. Analysis of these anomalies of diffraction patterns leads to the interpretation that the Kossel images including their fine structures are direct manifestations of the loci of gaps of the dispersion surface at the Brillouin-zone boundaries.