Open AccessPerformance of nearly fixed offset asymmetric channel‐cut crystals for X‐ray monochromators
Author(s) -
Frahm Ronald,
Diao Qianshun,
Murzin Vadim,
Bornmann Benjamin,
Lützenkirchen-Hecht Dirk,
Hong Zhen,
Li Tang
Publication year - 2019
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s1600577519011123
Subject(s) - offset (computer science) , optics , beam (structure) , crystal (programming language) , asymmetry , bragg peak , bragg's law , photon energy , channel (broadcasting) , materials science , photon , physics , diffraction , quantum mechanics , computer science , programming language , electrical engineering , engineering
X‐ray double‐crystal monochromators face a shift of the exit beam when the Bragg angle and thus the transmitted photon energy changes. This can be compensated for by moving one or both crystals accordingly. In the case of monolithic channel‐cut crystals, which exhibit utmost stability, the shift of the monochromated beam is inevitable. Here we report performance tests of novel, asymmetrically cut, channel‐cut crystals which reduce the beam movements by more than a factor of 20 relative to the symmetric case over the typical energy range of an EXAFS spectrum at the Cu K ‐edge. In addition, the presented formulas for the beam offset including the asymmetry angle directly indicate the importance of this value, which has been commonly neglected so far in the operation of double‐crystal monochromators.