title: Anisotropy of extinction: extrapolation to the kinematical limit by γ-ray diffraction.
abstract: A direct experimental approach to the problem of anisotropic extinction is presented. Structure-factor measurements from a vanadium and a niobium crystal, performed with four γ-ray wavelengths in the range 0.02-0.06 Å, substantiate the adequacy of Zachariasen's theory [Acta Cryst. (1967), 23, 558-564] in high-energy diffraction, which provides a theoretical basis for the extrapolation to zero extinction values. Fitting of the theoretical curve to the observed points, placed on a common scale, allows determination of the kinematical structure-factor value without the need for a particular model of anisotropy in the mosaic structure.
authors.affiliation: Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, D-14109 Berlin, Germany. jauch@helmholtz-berlin.de
authors.forename: W
authors.initials: W
authors.lastname: Jauch
authors.forename: M
authors.initials: M
authors.lastname: Reehuis