Direct determination of X-Ray reflection phases for noncentrosymmetric crystals

[[abstract]]An experimental method is described for the phase determination of x-ray reflections from noncentrosymmetric crystals. This method results from considerations on the phase dependence of line profiles in three-beam reflection-type diffractions for wavelength λ above and below a critical absorption edge λE of the heaviest constituent atom in the crystals. A relationS p =S L ·S R for phase determination is derived theoretically and verified experimentally forλ< λE ,S p being the sign of the sine of invariant phase,S L the sign defined from the line profile, andS R determined by the rotation of the crystal lattice.[[fileno]]2010105010084[[department]]物理