BL03HB: a Laue microdiffraction beamline for both protein crystallography and materials science at SSRF

A Laue microdiffraction beamline(BL03HB) was constructed at the Shanghai Synchrotron Radiation Facility(SSRF).This beamline features two consecutive focusing points in two different sectors within its end station, the first dedicated to protein crystallography and the other tailored to materials science applications. Based on a superbend dipole magnet with a magnetic field of 2.29 T, a two-stage focusing design was implemented with two sets of Kirkpatrick-Baez mirrors to achieve a micro white beam as small as 4.2 μ m ×4.3 μ m at the first sector and 0.9 μ m ×1.3 μ m at the second sector in the standard beamline operation mode at SSRF. The X-ray microbeam in the two sectors can be easily switched between monochromatic and white beams by moving a four-bounce monochromator in or out of the light path, respectively. In the protein crystallography sector, white-beam Laue microdiffraction was demonstrated to successfully determine the structure of protein crystals from only a few images of diffraction data collected by a Pilatus 2 M area detector. In the materials science sector,the white-beam Laue diffraction was collected in a reflection geometry using another Pilatus 2 M area detector, which could map the microstructural distribution on the sample surface by scanning the samples. In general, the BL03HB beamline promotes the application of Laue microdiffraction in both protein crystallography and materials science. This paper presents a comprehensive overview of the BL03HB beamline, end station, and the first commission results.

Intensity correlation properties of x-ray beams split with Laue diffraction

Beam splitting is one of the main approaches to achieving x-ray ghost imaging, and the intensity correlation between diffraction beam and transmission beam will directly affect the imaging quality. In this paper, we investigate the intensity correlation between the split x-ray beams by Laue diffraction of stress-free crystal. The analysis based on the dynamical theory of x-ray diffraction indicates that the spatial resolution of diffraction image and transmission image are reduced due to the position shift of the exit beam. In the experimental setup, a stress-free crystal with a thickness of hundredmicrometers-level is used for beam splitting. The crystal is in a non-dispersive configuration equipped with a double-crystal monochromator to ensure that the dimension of the diffraction beam and transmission beam are consistent. A correlation coefficient of 0.92 is achieved experimentally and the high signal-to-noise ratio of the x-ray ghost imaging is anticipated.Results of this paper demonstrate that the developed beam splitter of Laue crystal has the potential in the efficient data acquisition of x-ray ghost imaging.

Hard X-ray focusing resolution and efficiency test with a thickness correction multilayer Laue lens

The multilayer Laue lens(MLL) is a diffractive focusing optical element which can focus hard X-rays down to the nanometer scale. In this study, a WSi_(2)/Si multilayer structure consisting of 1736 layers, with a 7.2-nm-thick outermost layer and a total thickness of 17 μm, is prepared by DC magnetron sputtering. Regarding the thin film growth rate calibration, we correct the long-term growth rate drift from 2 to 0.6%, as measured by the grazing incidence X-ray reflectivity(GIXRR). A one-dimensional line focusing resolution of 64 nm was achieved,while the diffraction efficiency was 38% of the-1 order of the MLL Shanghai Synchrotron Radiation Facility(SSRF) with the BL15U beamline.

多层膜Laue透镜对10keV硬X射线聚焦性能的理论计算

采用NbC/Si材料组合设计多层膜Laue透镜,总膜厚为40μm,利用衍射动力学理论分析多层膜Laue透镜对硬X射线的衍射效率及聚焦分辨率。通过两种方法提高多层膜Laue透镜的分辨率。第一种方式是减小膜层的最外层宽度,该方法要求结构必须是楔型结构,制备极其困难。第二种方法是使用多层膜Laue透镜的高级次,该方法在不增加制备难题的前提下能有效提高分辨率。通过使用多层膜Laue透镜的-3级次,对10keV硬X射线获得了分辨率为6.72nm,衍射效率为49.31%的聚焦光斑。

Quantitative Analysis of Zero and High Order Laue Zones Effects on the Exit Wave Function

The exit wave function including zero and high order Laue zones has been simulated by both multi-slice method and electron dynamic diffraction analytical expression. Coincidence of the simulations by these two methods was achieved. The calculated results showed that the exit wave function highly dominated by zero order Laue zone, while high order ones modify the exit wave function to some extent depending on the situation. High order Laue zone effects become important for the following cases: sample consists of light elements, the thickness is very thin, lattice planar spacing perpendicular to the direction of the incident beam is large, and the electron beam has long wavelength. In these cases the exit wave function should be corrected by adding high order Laue zone effects. The analytical expression is effective and convenient for dealing with high order Laue zone effects.

Laue弯晶聚焦特性的光线追迹研究

由于可有效降低高热负载的影响,Laue弯晶是插入件辐射高通量密度硬X射线(30 keV以上)聚焦、准直和单色化的最有效的光学元件.研究其聚焦光学特性,对发展高性能、高稳定的Laue弯晶单色器具有重要意义.采用自行发展的光线追迹软件较为系统地研究了Laue弯晶的聚焦特性,分析了入射光性质及弯晶参数对聚焦光斑、焦距、发散度等主要光学参数的影响.结果表明,衍射能量越高,聚焦光斑越小,并趋于稳定值;弯曲半径越小,聚焦光斑越小,并在其达到一阈值时得到聚焦光斑的极小值,之后随着弯曲半径的变小,由于像差等因素的影响,聚焦光斑反而变大;晶体越厚,聚焦光斑越大,呈线性正比关系.对于衍射光发散度,其随着衍射能量的增大而变小,并趋于稳定值;其与晶体曲率呈线性正比关系.同时通过研究得到弯晶各参数的合理选择范围.

共振光子晶体中Laue孤子传播的动力学行为

从理论上研究了Laue孤子传播的动力学行为,并通过数值模拟验证了这些行为.结果表明,由于非线性衍射,入射脉冲会分裂产生四种模式,其中产生的Laue孤子的传播行为与一般共振介质中孤子的传播行为相似.

X-ray nanometer focusing at the SSRF based on a multilayer Laue lens

We designed and fabricated a multilayer Laue lens （MLL） as a hard X-ray focusing device. WSi2/Si multilayers were chosen owing to their excellent optical properties and relatively sharp interface. The multilayer sample was fabricated by using direct current （DC） magnetron sputtering technology and then was sliced and thinned to form an MLL. The thickness of each layer was determined by scanning electron microscopy （SEM） image analysis with marking layers. The focusing property of the MLL was measured at Beamline 15U, Shanghai Synchrotron Facility （SSRF）. One-dimensional （1D） focusing resolutions of 92 nm are obtained at photon energy of 14 keV.

Hard X-ray one dimensional nano-focusing at the SSRF using a WSi_2 /Si multilayer Laue lens

The multilayer Laue lens （MLL） is a novel diffraction optics which can realize nanometer focusing of hard X-rays with high efficiency. In this paper, a 7.9 μm-thick MLL with the outmost layer thickness of 15 nm is designed based on dynamical diffraction theory. The MLL is fabricated by first depositing the depth-graded multilayer using direct current （DC） magnetron sputtering technology. Then, the multilayer sample is sliced, and both cross-sections are thinned and polished to a depth of 35–41 μm. The focusing property of the MLL is measured at the Shanghai Synchrotron Facility （SSRF）. One-dimensional （1D） focusing resolutions of 205 nm and 221 nm are obtained at E=14 keV and 18 keV, respectively. It demonstrates that the fabricated MLL can focus hard X-rays into nanometer scale.

ON THE INTENSITY OF LAUE DIFFRACTION

Laue method is classical in X-ray analysis of crystals. Its diffraction spots are produced by the continuous spectrum of incident X-rays, in which the changeable wavelength can fit in with the different hkl diffraction conditions.

X-ray focusing with efficient high-NA multilayer Laue lenses

Multilayer Laue lenses are volume diffraction elements for the efficient focusing of X-rays.With a new manufacturing technique that we introduced,it is possible to fabricate lenses of sufficiently high numerical aperture(NA)to achieve focal spot sizes below 10 nm.The alternating layers of the materials that form the lens must span a broad range of thicknesses on the nanometer scale to achieve the necessary range of X-ray deflection angles required to achieve a high NA.This poses a challenge to both the accuracy of the deposition process and the control of the materials properties,which often vary with layer thickness.We introduced a new pair of materials—tungsten carbide and silicon carbide—to prepare layered structures with smooth and sharp interfaces and with no material phase transitions that hampered the manufacture of previous lenses.Using a pair of multilayer Laue lenses(MLLs)fabricated from this system,we achieved a two-dimensional focus of 8.4×6.8 nm2 at a photon energy of 16.3 keV with high diffraction efficiency and demonstrated scanning-based imaging of samples with a resolution well below 10 nm.The high NA also allowed projection holographic imaging with strong phase contrast over a large range of magnifications.An error analysis indicates the possibility of achieving 1 nm focusing.

上海同步辐射装置医学应用光束线和实验站物理设计

完成了上海同步辐射装置医学应用光束线和实验站的物理设计，并开始了有关技术设计及其难点的初步考虑。采用一个磁场强度为1.8T、周期数为10的多极扭摆器为冠状动脉心血管造提供所需的强X光束；利用一块Laue弯晶Si(111)单色器可得到比所需大三倍、能量分别在碘吸收边上下的二束单色X光束；造影过程将通过病人座椅的扫描运动和一个双列线形探测器来实现。

直角杠杆佯谬和受压动体的劳厄能流

直角杠杆所受力矩的相对论变换体现出转动佯谬〔1,2 ,3〕.本文通过深入分析受压动体内应力功能关系 ,进一步证实了劳厄能流是客观存在的事实 。

巧妙的构想 大胆的创新——劳厄与X射线衍射的实验

通过劳厄对X射线衍射的实验构想 ,来展现他的思维方法的独创性 ,从中得到对我们的科学研究工作的启迪 .

X射线晶体学的百年辉煌

自1912年劳厄发现X射线晶体衍射现象,小布拉格开创X射线晶体学以来,已经过去了100年。这一发现,对人类科学的发展,特别是微观结构科学的影响至为巨大,具有里程碑的意义。在这100年中,X射线晶体学发展迅速,成果累累。本文按主要实验技术的特点将100年大致分为四个阶段,从单晶体衍射、多晶体衍射和X射线光谱三个方面简述其主要进展和成果。并简单概括了她对物理学、晶体学、化学和生物学等基础学科和材料、医药、环境等多个应用学科的重大影响。最后,还预期了X射线晶体学领域的一些可能发展,包括无比强大的光源—硬X射线自由电子激光、多维晶体学、电子晶体学、数学晶体学、三维X射线衍射显微学等领域。作者相信,X射线晶体学在过去的一个世纪中已经取得了那么多的成就,在已来临的新世纪中将会获得更大的成绩。

一种消除弯晶面形扭曲的轴角装置

Laue晶体单色器常用于单色化高能X射线(>50keV),通过对其晶片压弯可以实现高能光束聚焦。晶片压弯过程中会不可避免地产生扭曲,从而影响单色器的工作效率。利用波动光学仿真的方法,分析弯晶面形扭曲对Laue晶体单色器性能的影响,并提出一种角位移微调轴角装置,用来消除这种扭曲。该装置基于直梁型柔性铰链,利用叠加原理和对称结构。利用有限元方法分析了该装置的力学性能。分析结果表明,轴角装置的转角范围为±2°时,其转动中心最大偏移为20μm,实现了角位移分辨率好于1″,动态范围达到104,达到设计目标。

智能化劳厄定向法

提出了晶体劳厄定向的智能化方法；简述了有关的Ｘ射线衍射理论、数学模型和运行步骤；讨论了该方法的可靠性和实用性．

SiC_f/Ti-6Al-4V基复合材料界面晶格常数变化的CBED研究

本实验采用会聚束电子衍射(CBED)方法,研究3种不同状态SiCf/Ti-6Al-4V复合材料界面附近α-Ti晶粒的晶格常数变化。结果表明:在纤维-基体界面区域,靠近界面处晶格常数变化较大,随距界面反应层距离增大,晶格常数的变化趋近缓慢。有C涂层SiC纤维制成的复合材料中晶格常数变化比无C涂层复合材料晶格常数变化小。相比制备态复合材料,热暴露无C涂层SiCf/Ti-6Al-4V复合材料界面处,晶格常数变化较为缓和。

劳厄对晶体衍射的发现

介绍了劳厄提出晶体衍射思想的科学背景及当时的实验过程,并探讨在劳厄发现晶体衍射的过程中其科学思想的形成及X射线晶体衍射的发现带给我们的启示及影响.

(Nd^(3+),Yb^(3+))∶Ca_3(VO_4)_2晶体的极化研究

本文回顾了 (Nd3+ ,Yb3+ )∶Ca3(VO4 ) 2 晶体的研究历程 ,通过对晶体结构和对晶体激光性能研究年代的对比 ,认为高的泵浦阈值是由于晶体中存在的对泵浦光和激光散射很强的畴壁结构未被发现而造成的。讨论了极化的原理、建立了极化装置 ,采用Laue定向法和X射线定向仪定向法结合解决了 (Nd3+ ,Yb3+ )∶Ca3(VO4 ) 2 这种大晶格常数 (c =3.80 2 9nm)晶体的定向问题。把晶体的抛光面放入 0 .5mol%的温度为 30℃的硼酸中腐蚀样品 1h ,用显微镜可以观察到畴结构。在～ 110 0℃和电流密度为～ 10 μA/mm2 的条件下极化 2h即可完成极化。变黑的极化样品可以通过把晶体放入马福炉中升温至 850℃ ,保持 1h ,然后降至室温即可消除。