Sztucki Michael, Leonardon Joachim, Van Vaerenbergh Pierre, Gorini Jacques, Boesecke Peter, Narayanan Theyencheri
European Synchrotron Radiation Facility, CS 40220, 38043 Grenoble Cedex 9, France.
J Synchrotron Radiat. 2019 Mar 1;26(Pt 2):439-444. doi: 10.1107/S1600577518016892. Epub 2019 Jan 25.
Crystal collimation offers a viable alternative to the commonly used pinhole collimation in small-angle X-ray scattering (SAXS) for specific applications requiring highest angular resolution. This scheme is not affected by the parasitic scattering and diffraction-limited beam broadening. The Darwin width of the rocking curve of the crystals mainly defines the ultimate beam divergence. For this purpose, a dispersive Si-111 crystal collimation set-up based on two well conditioned pseudo channel-cut crystals (pairs of well polished, independent parallel crystals) using a higher-order reflection (Si-333) has been developed. The gain in resolution is obtained at the expense of flux. The system has been installed at the TRUSAXS beamline ID02 (ESRF) for reducing the horizontal beam divergence in high-resolution mesurements. The precise mechanics of the system allows reproducible alignment of the Bragg condition. The high resolution achieved at a sample-detector distance of 31 m is demonstrated by ultra-small-angle X-ray scattering measurements on a model system consisting of micrometre-sized polystyrene latex particles with low polydispersity.
对于需要最高角分辨率的特定应用，在小角X射线散射（SAXS）中，晶体准直为常用的针孔准直提供了一种可行的替代方案。该方案不受寄生散射和衍射极限光束展宽的影响。晶体摇摆曲线的达尔文宽度主要决定了最终的光束发散度。为此，已开发出一种基于两个条件良好的伪通道切割晶体（两对精心抛光的独立平行晶体）、利用高阶反射（Si-333）的色散Si-111晶体准直装置。分辨率的提高是以通量为代价的。该系统已安装在TRUSAXS光束线ID02（欧洲同步辐射装置）上，用于在高分辨率测量中减小水平光束发散度。该系统精确的机械装置可实现布拉格条件的可重复对准。在由低多分散性的微米级聚苯乙烯乳胶颗粒组成的模型系统上进行的超小角X射线散射测量表明，在样品-探测器距离为31 m时可实现高分辨率。
