Kozhevnikov I V, Filatova E O, Sokolov A A, Konashuk A S, Siewert F, Störmer M, Gaudin J, Keitel B, Samoylova L, Sinn H
Shubnikov Institute of Crystallography, Russian Academy of Sciences, Leninsky Prospect 59, Moscow 119333, Russian Federation.
St Petersburg State University, Ulyanovskaya 3, Peterhof, St Petersburg 198504, Russian Federation.
J Synchrotron Radiat. 2015 Mar;22(2):348-53. doi: 10.1107/S1600577515000430. Epub 2015 Feb 11.
The use of soft X-rays near the carbon edge of absorption (270-300 eV) greatly enhances studies in various branches of science. However, the choice of reflecting coatings for mirrors operating in free-electron and X-ray free-electron laser (FEL and XFEL) beamlines in this spectral range is not so evident and experimental justifications of the mirror efficiency are rather limited. In the present paper it is demonstrated experimentally that the reflectivity of B4C- and Ni-coated grazing-incidence mirrors is high enough for their operation in FEL or XFEL beamlines near the carbon K-edge of absorption. The minimal reflectivity of both mirrors proves to exceed 80% near the carbon absorption edge at a grazing angle of 0.6°. An in-depth profile of the chemical elements composing the reflecting coatings is reconstructed based on analysis of a set of reflectivity curves measured versus the grazing angle at different photon energies in the soft X-ray spectral region. This allows us to predict correctly the mirror reflectivity at any X-ray energy and any grazing angle.
在碳吸收边缘附近（270 - 300电子伏特）使用软X射线极大地促进了各科学分支的研究。然而，在该光谱范围内，用于自由电子和X射线自由电子激光（FEL和XFEL）光束线中运行的镜子的反射涂层选择并不那么明显，并且镜子效率的实验依据相当有限。在本文中，通过实验证明，B4C涂层和Ni涂层的掠入射镜的反射率足够高，可在碳K吸收边缘附近的FEL或XFEL光束线中运行。在掠射角为0.6°时，两种镜子在碳吸收边缘附近的最小反射率均超过80%。基于对软X射线光谱区域不同光子能量下与掠射角相关的一组反射率曲线的分析，重建了构成反射涂层的化学元素的深度分布。这使我们能够正确预测任意X射线能量和任意掠射角下的镜子反射率。
