Gog Thomas, Casa Diego M, Knopp Jonathan, Kim Jungho, Upton Mary H, Krakora Richard, Jaski Alan, Said Ayman, Yavaş Hasan, Gretarsson Hlynur, Huang Xian Rong
Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Lemont, IL 60439, USA.
Deutsches Elektronen Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany.
J Synchrotron Radiat. 2018 Jul 1;25(Pt 4):1030-1035. doi: 10.1107/S1600577518005945. Epub 2018 May 31.
In the context of a novel, high-resolution resonant inelastic X-ray scattering spectrometer, a flat-crystal-based quartz analyzer system has recently been demonstrated to provide an unprecedented intrinsic-energy resolution of 3.9 meV at the Ir L absorption edge (11.215 keV) [Kim et al. (2018) Sci. Rep. 8, 1958]. However, the overall instrument resolution was limited to 9.7 meV because of an 8.9 meV incident band pass, generated by the available high-resolution four-bounce Si(844) monochromator. In order to better match the potent resolving power of the novel analyzer with the energy band pass of the incident beam, a quartz(309)-based double-bounce, high-resolution monochromator was designed and implemented, expected to yield an overall instrument resolution of 6.0 meV. The choice of lower-symmetry quartz is very attractive because of its wealth of suitable near-backscattering reflections. However, it was found that during room-temperature operation typical levels of incident power, barely affecting the Si monochromator, caused substantial thermal distortions in the first crystal of the quartz monochromator, rendering it practically unusable. Finite-element analyses and heat-flow analyses corroborate this finding. As a high-flux, lower resolution (15.8 meV) alternative, a two-bounce sapphire(078) version was also tested and found to be less affected than quartz, but notably more than silicon.
在一种新型高分辨率共振非弹性X射线散射光谱仪的背景下，最近已证明基于平面晶体的石英分析仪系统在Ir L吸收边（11.215 keV）处可提供前所未有的3.9 meV本征能量分辨率[Kim等人（2018年），《科学报告》8, 1958]。然而，由于可用的高分辨率四反射Si(844)单色仪产生的8.9 meV入射带通，整体仪器分辨率限制为9.7 meV。为了使新型分析仪的强大分辨能力与入射光束的能带通更好地匹配，设计并实现了基于石英(309)的双反射高分辨率单色仪，预计整体仪器分辨率为6.0 meV。选择较低对称性的石英很有吸引力，因为它有大量合适的近背散射反射。然而，发现在室温运行期间，典型的入射功率水平对Si单色仪几乎没有影响，但却在石英单色仪的第一晶体中引起了严重的热畸变，使其实际上无法使用。有限元分析和热流分析证实了这一发现。作为一种高通量、低分辨率（15.8 meV）的替代方案，还测试了双反射蓝宝石(078)版本，发现其受影响程度比石英小，但明显比硅大。
