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Spatial displacement of forward‐diffracted X‐ray beams by perfect crystals
Author(s) -
Rodriguez-Fernandez A.,
Esposito V.,
Sanchez D. F.,
Finkelstein K. D.,
Juranic P.,
Staub U.,
Grolimund D.,
Reiche S.,
Pedrini B.
Publication year - 2018
Publication title -
acta crystallographica section a
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.742
H-Index - 83
ISSN - 2053-2733
DOI - 10.1107/s2053273318001419
Subject(s) - bragg's law , diffraction , optics , femtosecond , diffraction topography , laser , physics , free electron laser , displacement (psychology) , dynamical theory of diffraction , electron , reflection (computer programming) , crystal (programming language) , electron diffraction , free electron model , materials science , acousto optics , diffraction grating , quantum mechanics , psychology , computer science , psychotherapist , programming language
Time‐delayed, narrow‐band echoes generated by forward Bragg diffraction of an X‐ray pulse by a perfect thin crystal are exploited for self‐seeding at hard X‐ray free‐electron lasers. Theoretical predictions indicate that the retardation is strictly correlated to a transverse displacement of the echo pulses. This article reports the first experimental observation of the displaced echoes. The displacements are in good agreement with simulations relying on the dynamical diffraction theory. The echo signals are characteristic for a given Bragg reflection, the structure factor and the probed interplane distance. The reported results pave the way to exploiting the signals as an online diagnostic tool for hard X‐ray free‐electron laser seeding and for dynamical diffraction investigations of strain at the femtosecond timescale.