Three-beam diffraction in a finite perfect crystal

Thorkildsen, Gunnar

doi:10.1107/s010876738709929x

Cited by 58 publications

(15 citation statements)

References 17 publications

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“…For this reason a perturbational theory based on a second-order Born approximation 5-7 has so far been used in reference-beam data analysis, 1,2 which gives good descriptions on the wings of a reference-beam interference profile but is often invalid near the center of the reference-reflection rocking curve. In addition, phaseindependent contributions [7][8][9] to the diffracted intensity are either incorrectly calculated or completely omitted in the perturbational approach.…”

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confidence: 99%

Distorted-wave approach to reference-beam x-ray diffraction in transmission cases

Shen

2000

Phys. Rev. B

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The conventional distorted-wave theory for x-ray scattering from surfaces is expanded to account for phasesensitive reference-beam diffraction in bulk crystals. The expanded theory, presented here for the transmission geometry that is suitable for biological specimens, provides a simple intensity formula with an explicit dependence on the phases of the structure factors. Numerical results show excellent agreement with full dynamical calculations. Based on this theory, a universal optimal condition is proposed for maximizing the referencebeam interference effects in an experiment.

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confidence: 99%

Distorted-wave approach to reference-beam x-ray diffraction in transmission cases

Shen

2000

Phys. Rev. B

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“…An alternative approach, utilizing a combined !=step scan, may cause an unwanted broadening of the profiles, cf. Thorkildsen (1987) and Mo et al (1998). As pointed out by Shen (1993), the natural beam divergence will inherently provide a partial !…”

Section: Figurementioning

confidence: 95%

Three-beam resonant X-ray diffraction in germanium – Laue transmission cases

Thorkildsen

Larsen

Weckert³

et al. 2005

Acta Cryst Sect A

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Perturbation of the two-beam diffracted power owing to the influence of a third lattice node has been examined for various three-beam cases in a small finite germanium crystal in the vicinity of the K-absorption edge. Although the crystal was slightly imperfect, the main parts of the experimental results are very well described within the framework of the fundamental theory of X-ray diffraction in conjunction with Cromer-Liberman calculations for the resonant scattering terms. Beam divergence and dynamical block size are treated as adjustable parameters in the analysis. Observed changes in the three-beam profile asymmetry are mainly attributed to size and not to resonance effects associated with the triplet phase sum of the involved reflections. Close to the absorption edge there is however some evidence indicating that f' values should be reduced in magnitude compared to the tabulated ones.

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“…Quantitative computer analysis discussed later is based on the plane-wave dynamical theory using boundary conditions for parallel sided crystal slabs. Thorkildsen (1987) published the solution of dynamical three-beam diffraction by means of Takagi-Taupin equations for a parallelepiped shaped crystal. The extension of this work could be a way to solve the problem for arbitrarily shaped crystals.…”

Section: Introductionmentioning

confidence: 99%