Phys. Rev. Lett. 97, 235502 (2006) [4 pages]X-Ray Bragg Diffraction in Asymmetric Backscattering GeometryReceived 9 May 2006; published 8 December 2006 We observe three effects in the Bragg diffraction of x rays in backscattering geometry from asymmetrically cut crystals. First, exact Bragg backscattering takes place not at normal incidence to the reflecting atomic planes. Second, a well-collimated (≃1 μrad) beam is transformed after the Bragg reflection into a strongly divergent beam (230 μrad) with reflection angle dependent on x-ray wavelength—an effect of angular dispersion. The asymmetrically cut crystal thus behaves like an optical prism, dispersing an incident collimated polychromatic beam. The dispersion rate is ≃8.5 mrad/eV. Third, parasitic Bragg reflections accompanying Bragg backreflection are suppressed. These effects offer a radically new means for monochromatization of x rays not limited by the intrinsic width of the Bragg reflection. URL:
http://link.aps.org/doi/10.1103/PhysRevLett.97.235502
DOI:
10.1103/PhysRevLett.97.235502
PACS:
61.10.−i, 41.50.+h, 42.25.Fx
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