X-Ray Multiple Diffraction and the Invariant Phases of Structure Factors

張石麟(Shih-Lin Chang)

《Chinese Journal of Physics》 23卷3期 (1985/10) Pp. 181-192

並列摘要

A brief review is given to multiple diffraction of X-rays in crystals in relation to the experimental determination of the invariant phases of the structure-factor products, such as triplets and quartets. The relationship between multiply diffracted intensities/wavefields and the phases is re-examined based on the classical dynamical theory of X-ray diffraction. The fundamental equation of wavefields and dispersion relation of wavevectors are employed to reveal the phase dependence of wavefields and wavevectors. Calculated multiple diffraction intensity line profiles are compared with the experimentally obtained ones. Phase information extracted from this comparison is presented for centrosymmetric crystals. The difficulties in phase determination for noncentrosymmetric crystals are analyzed. The wavelength dependence of intensity line-profile in acentric crystals obtained experimentally using conventional and synchrotron radiation sources is reported.