同步辐射软X射线显微成像

软X射线显微成像是同步辐射最主要的应用之一,本文简明介绍软X射线显微成像的衬度机制,光源,成像方法和一些应用结果。     

Study of the microstructure of a HCP zirconium alloy using synchrotron radiation X-ray diffraction

Synchrotron radiation X-ray diffraction has been applied for the precision study of the micro-structure evolution of a Zr-1% Nb alloy deformed by uniaxial tension. A nonmonotonic pattern of the integral width of X-ray lines as a function of in situ deformation and acting stress has been revealed, which is in agreement with intensity fluctuations of reflections and elastic microdistortions related to structural imperfection. The obtained results correlate with transmission electron microscopy data on the cyclicity of dislocation transformations during necking.     

X-ray diffraction studies of Pompeian wall paintings using synchrotron radiation and dedicated laboratory made systems

The full identification of artwork materials requires not only elemental analysis but also structural information of the compounds as provided by X-ray diffraction (XRD). This is easily done when taking samples (or micro-samples) from artworks. However, there is an increasing interest in performing non-destructive studies that require adapted XRD systems. Comparative study of synchrotron high-resolution X-ray powder diffraction (SR-HRPD) and laboratory non-destructive systems (portable XRD and micro-XRD) is the main objective of this work. There are no qualitative differences among the three systems as for detected phases in the Pompeian wall paintings that were studied, except in the case of minority phases which only were detected by SR-HRPD. The identified pigments were goethite, hematite, cinnabar, glauconite, Pompeian blue, together with calcite, dolomite and aragonite. Synchrotron XRD diagrams show better resolution than the others. In general, the peak widths in the diagrams obtained with the portable XRD system are similar to those obtained by micro-diffraction equipment. Factors such as residual divergence of X-ray sources, incidence angle and slit or collimator size are discussed in relation with the quality of XRD diagrams.     

Confocal three-dimensional micro X-ray fluorescence based on synchrotron radiation for mineral analysis

The confocal three-dimensional micro X-ray fluorescence using polycapillary optics and a synchrotron radiation was applied to nondestructively analyze elemental compositions of minerals, and thereby obtain the three-dimensional distributions of elements in the minerals. Such confocal micro X-ray fluorescence had potential applications in the mineral prospecting, identification of jades, differentiation of stones.     

Investigation of nanostructured Fe3O4 polypyrrole core-shell composites by X-ray absorbtion spectroscopy and X-ray diffraction using synchrotron radiation

In this article, we focus on the structural peculiarities of nanosized Fe₃O₄ in the core-shell nanocomposites obtained by polymerization of conducting polypyrrole shell around Fe₃O₄ nanoparticles. The local structure of Fe atoms was determined from the Extended X-ray Absorption Fine Structure analysis using our own package computer programs. An X-ray diffraction method that is capable to determine average particle size, microstrains, as the particle size distribution of Fe₃O₄ nanoparticles is presented. The method is based on the Fourier analysis of a single X-ray diffraction profile using a new fitting method based on the generalized Fermi function facilities. The crystallites size obtained by X-ray diffraction spectra analysis was estimated between 3.2 and 10.3 nm. Significant changes in the first and the second Fe coordination shell in comparison with standard bulk were observed. The global and local structure of the nanosized Fe₃O₄ are correlated with the synthesis conditions of the core-shell polypyrrole nanocomposites.     

X-ray microfluorescence with synchrotron radiation applied in the analysis of pigments from ancient Egypt

In this work, X-ray microfluorescence with the synchrotron radiation technique was applied in the analysis of pigments found in decorative paintings in the sarcophagus of an Egyptian mummy. This female mummy, from the Roman Period, which was embalmed with the arms and legs swathed separately is considered one of the most important pieces of the Egyptian Collection from the National Museum (Rio de Janeiro, Brazil). The measurements were performed at the XRF beamline D09B of the Brazilian Synchrotron Light Laboratory (LNLS), using the white beam and a Si(Li) detector with resolution of 165 eV at 5.9 keV. The possible pigments found in the samples were: Egyptian blue, Egyptian green frit, green earth, verdigris, malachite, ochre, realgar, chalk, gypsum, bone white, ivory black and magnetite. Hierarchical cluster analysis (HCA) and principal component analysis (PCA) were applied to the results in order to verify if the samples belong to the same period of a linen wrapping fragment, whose provenance was well established. PACS 07.85.Nc; 07.85.Qe; 78.70.En     

X-ray synchrotron radiation in medium

Energy and angular distributions of X-ray synchrotron radiation produced by an ultra relativistic electron moving in a medium are discussed. Calculations show that the medium suppresses strongly the yield of the radiation for the electron Lorentz factor smaller than some cut-off value depending on the medium electron density and magnetic field applied.     

X-ray lithography with synchrotron radiation

Manufactures of silicon integrated circuits increasingly rely on high resolution, high throughput, and litography techniques based on parallel mask projection. The once simple technique of projecting an image of a mask on a wafer, however, is now being replaced by more elaborate systems at an ever faster rate. Of the possible successors to photolithography in the production of structures smaller than 0.7 m, the most promising appears to be X-ray litography with synchrotron radiation. The development problems of this new technique are related to the mask technology, alignment systems, resist materials, and compact, low-cost storage rings.     

高压下的同步辐射能量色散粉末衍射

 同步辐射已经成为高压研究的一个非常理想的光源。在北京同步辐射装置（BSRF）上、结合金刚石对顶砧超高压实验技术建立起来的能量色散X射线粉末衍射系统,已用于物质状态方程和结构相变的研究。介绍了能量色散衍射方法,以及同步辐射原位测试过程。     

Angular dispersive diffraction using a diamond-anvil pressure cell and synchrotron X-ray source

Abstract

Wavelength dispersive diffraction studies have been performed using a diamond-anvil pressure cell and bending magnet synchrotron produced radiation. A double-crystal monochromator was used to select 15 and 17 keV photons and a 80 μm diameter collimator was used to restrict the beam entering the pressure cavity. Parallelism between the incident beam and the collimator axis was assisted by computer control of the collimator. The image of the transmitted beam was observed using a Hamamatsu x-ray Vidicon and TV monitor, for this alignment. The diffracted beam was recorded on x-ray film using a double film cassette and exposure times ranged from 6 to 8 hours. Neither the exposure time nor the line width of the diffraction lines was significantly altered by replacement of the incident beam collimator with a slit system.     

Investigation of craze development using small-angle X-ray scattering of synchrotron radiation

The development of crazes in polycarbonate was investigated with the method of ultra-small-angle X-ray scattering (USAXS) of synchrotron radiation. Measurements at different temperatures and with different draw rates were carried out. The two-dimensional scattering patterns were analyzed by means of a fibrillar model of the craze. The geometrical parameters of the craze as a function of the macroscopic draw ratio were determined by using a curve-fitting procedure. From the measured values of the diameter and the mean distance of the fibrils, it is possible to calculate the volume fraction v_f of the fibrils directly. Additional scattering caused by submicrocracks is discussed.     

X-ray magnetooptics based on synchrotron radiation

The conditions for obtaining a maximum magnetic signal in different experiment geometries have been analyzed on the basis of the general theory of reflection from a layered anisotropic medium. It is shown that, in the equatorial geometry in Bragg reflections from a periodic structure with antiferromagnetic interlayer ordering, amplification of linear dichroism arises, which can be observed even in the grazing geometry.     

用同步辐射X射线衍射技术分析GaN/Si外延膜的结构与应变

选用有AlN和AlGaN缓冲层的GaN/Si作为测试样品,采用同步辐射X射线衍射(SRXRD)技术对样品外延膜(GaN)的几何结构、晶格常量及其应变进行了分析.结果表明,同步辐射X射线衍射实验可以作为一种有效的技术手段,测试固体结构及应变.     

Coplanar three-beam X-ray diffraction study in TeO<Subscript>2</Subscript> single crystal using synchrotron radiation

The results of the first experimental study of coplanar three-beam X-ray diffraction in a paratellurite (TeO₂) single crystal using synchrotron radiation on a Kurchatov synchrotron radiation source are presented. Four cases with (220, 371), (220, 464), (220, 370), and (110, 557) indices have been investigated. In all cases the change of the rocking curve shape of the weak reflection has been observed due to the multibeam interaction resulting in the appearance of two peaks in the reflection curve corresponding to two scattering mechanisms: amplitude and resonance. The origin of the insufficient resolution in the experiments has been considered. It has been shown that the obtained data correspond to the results of the computer simulation.     

Non-destructive synchrotron X-ray diffraction mapping of a Roman painting

The history and the properties of materials are deduced not only from their elemental and molecular signatures, but also from their exact phase compositions, and from the structures and the defects of their constituents. Here we implement a non-destructive synchrotron X-ray based method, which combines both the quantitative structural content of diffraction and the imaging mode. As a demonstration case, the pigments of a Roman wall painting are examined. The joined elemental and mineral maps mimic the major features of the painting. Different structural phases made of common atomic elements are differentiated. Textures and graininess are measured and related to the artist’s know-how. PACS 07.85.Qe; 61.10.Nz; 83.85.Hf     

High pressure x-ray diffraction techniques with synchrotron radiation

This article summarizes the developments of experimental techniques for high pressure x-ray diffraction(XRD) in diamond anvil cells(DACs) using synchrotron radiation. Basic principles and experimental methods for various diffraction geometry are described, including powder diffraction, single crystal diffraction, radial diffraction, as well as coupling with laser heating system. Resolution in d-spacing of different diffraction modes is discussed. More recent progress, such as extended application of single crystal diffraction for measurements of multigrain and electron density distribution, timeresolved diffraction with dynamic DAC and development of modulated heating techniques are briefly introduced. The current status of the high pressure beamline at BSRF(Beijing Synchrotron Radiation Facility) and some results are also presented.     

Observation of magnetic domain wall movements by X-ray topography using synchrotron radiation

Antiferromagnetic domain wall movements in KNiF₃ have been observed directly by X-ray topography using synchrotron radiation. Topographs were taken in fields up to 1.3 T at a temperature of 77 K. In contrast to X-ray topography using conventional sources, the apparatus is simple and it is possible to obtain good resolution topographs despite the geometrical limitations imposed by the cryostat and electromagnet. Exposure times were typically 8 seconds when recording on Ilford L4 Nuclear Emulsion plates.