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Dispersive spread of virtual sources by asymmetric X‐ray monochromators
Author(s) -
Huang X. R.,
Macrander A. T.,
Honnicke M. G.,
Cai Y. Q.,
Fernandez Patricia
Publication year - 2012
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889812003366
Subject(s) - beamline , optics , synchrotron , dispersion (optics) , synchrotron radiation , bragg's law , reflection (computer programming) , physics , spectroscopy , scattering , beam (structure) , materials science , computer science , diffraction , quantum mechanics , programming language
The principles of the virtual source spread (spatial broadening) phenomenon induced by angular dispersion in asymmetric X‐ray Bragg reflections are illustrated, from which the virtual source properties are analyzed for typical high‐resolution multiple‐crystal monochromators, including inline four‐bounce dispersive monochromators, back‐reflection‐dispersion monochromators and nondispersive nested channel‐cut monochromators. It is found that dispersive monochromators can produce spread virtual sources of a few millimetres in size, which may prevent efficient microfocusing of the beam as required by inelastic X‐ray scattering spectroscopy and other applications. Possible schemes to mitigate this problem are discussed. The analyses may provide important guidelines for designing and optimizing modern high‐precision synchrotron X‐ray optics and beamline instrumentation for spectroscopy, imaging and nanofocusing applications.