KOSSEL DIFFRACTION AND X-RAY STANDING WAVES - 2 BIRDS OF ONE FEATHER

By virtue of the optical reciprocity theorem, Bragg-case Kossel diffra ction in perfect crystals can be viewed as the reverse process of x-ra y standing waves (XSW) in the sense that the location of the source of radiation and the point of detection are merely interchanged between the two. A method can then be devised to determine atomic positions in a crystal lattice by analyzing the profile of angularly resolved Koss el lines, yielding equivalent information as an analogous XSW experime nt would. Technical aspects of this novel method are discussed and fir st experimental results involving Ge and Er:LiNbO3 single crystal samp les are presented, indicating that the equivalence between Kossel diff raction and XSW is indeed realized.