GISAXS and SAXS studies on the spatial structures of Co nanowire arrays

The spatial structures of magnetic Co nanowire array embedded in anodic aluminium membranes were investigated by grazing incidence small angle X-ray scattering (GISAXS) and conventional small angle X-ray scattering (SAXS) techniques. Compared with SEM observation, the GISAXS and SAXS measurements can get more overall structural information in a large-area scale. In this study, the two-dimensional GISAXS pattern was well reconstructed by using the IsGISAXS program. The results demonstrate that the hexagonal lattice formed by the Co nanowires is distorted (a ≈ 105 nm, b ≈ 95 nm). These Co nanowires are isolated into many structure domains with different orientations with a size of about 2 μm. The SAXS results have also confirmed that the nanopore structures in the AAM can be retained after depositing Co nanowires although the Co nanowires can not completely but only just fill up the nanopores. These results are helpful for understanding the global structure of the Co nanowire array.     

用于同步辐射光源的成像板粉末衍射系统

报道了我们研制的一套成像板粉末衍射装置,对其误差来源进行了详细的分析讨论,并与衍射仪进行了比较.该装置的半径为143.3mm,最大测量角度范围不160°，最大角度(2q )偏差小于0.03°,这些性能指标已被实验所证实,完全可应用于粉末衍射全谱的测量.     

Hierarchical structure and biomineralization in cricket teeth

The cricket is a truculent insect with stiff and sharp teeth as a fighting weapon. The structure and possible biomineralization of cricket teeth are always interesting. Synchrotron radiation X-ray fluorescence, X-ray diffraction, and small angle X-ray scattering techniques were used to probe the element distribution, possible crystalline structures and size distribution of scatterers in cricket teeth. A scanning electron microscope was used to observe the nanoscaled structure. The results demonstrate that Zn is the main heavy element in cricket teeth. The surface of a cricket tooth has a crystalline compound like ZnFe2(AsO4)2(OH)2(H2O)4 . The interior of the tooth has a crystalline compound like ZnCl2 , which is from the biomineralization. The ZnCl2-like biomineral forms nanoscaled microfibrils and their axial direction points towards the top of the tooth cusp. The microfibrils aggregate randomly into intermediate filaments, forming a hierarchical structure. A sketch map of the cricket tooth cusp is proposed and a detailed discussion is given in this paper.     

2-吡喃酮的催化不对称Diels-Alder反应研究进展

2-吡喃酮是一种含有共轭二烯的杂环化合物,它可以作为一种特殊的双烯体参与Diels-Alder反应.经过几十年的发展,2-吡喃酮的Diels-Alder反应在复杂天然产物的合成中得到了广泛地应用.近年来,2-吡喃酮的催化不对称Diels-Alder反应也引起了合成化学家的关注.对2-吡喃酮参与的不对称正电子需求和反电子需求的Diels-Alder反应的发展,以及它们在天然产物全合成中的应用进行了总结.     

用SAXS和XRD方法研究TiO2纳米颗粒微观结构

用溶胶-凝胶方法制备了TiO₂纳米样品,并对该样品在300℃到800℃温度区域进行了退火处理.应用同步辐射X射线粉末衍射(XRD)方法研究了经不同热处理温度的TiO₂纳米颗粒的结构相变.应用同步辐射小角X射线散射(SAXS)方法研究了TiO₂纳米颗粒的表面分形与界面特性.得到纳米颗粒粒度与退火温度的变化规律,讨论了表面界面特征与相变的关系. 关键词： X射线小角散射 X射线衍射 2纳米颗粒')" href="#">TiO₂纳米颗粒     

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(＞50 keV)，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20 μm，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。     

用SAXS和XRD方法研究Ti02纳米颗粒微观结构

用溶胶一凝胶方法制备了TiO2纳米样品.并对该样品在300℃到800℃温度区域进行了退火处理.应用同步辐射x射线粉未衍射(XRD)方法研究了经不同热处理温度的TiO2纳米颗粒的结构相变.应用同步辐射小角x射线散射(SAXS)方法研究了TiO2纳米颗粒的表面分形与界面特性.得到纳米颗粒粒度与退火温度的变化规律,讨论r表面界面特征与相变的关系.