由于X射线吸收精细结构（X—rayabsorption fine structure，XAFS）可以原位探测吸收原子的2～3个邻近配位壳层，获得目标元素的电子结构信息和化学结构信息，所以XAFS已成为微观领域最重要的结构分析工具，丰富了我们对元素的重要化学...由于X射线吸收精细结构（X—rayabsorption fine structure，XAFS）可以原位探测吸收原子的2～3个邻近配位壳层，获得目标元素的电子结构信息和化学结构信息，所以XAFS已成为微观领域最重要的结构分析工具，丰富了我们对元素的重要化学性质和反应过程的认识。本文简述了XAFS的基本原理，探讨了样品制备、测试及数据分析等过程需关注的问题，重点综述了应用XAFS研究土壤重金属和营养元素的形态、土壤固一液界面的反应过程和机理，并指出其应用的局限性和未来发展的前景，旨在推动我国XAFS在土壤科学中的应用。由于土壤中界面反应的复杂性，XAFS应结合其他结构分析技术，结构分析技术应结合宏观数据和计算机模拟，土壤学应与其他学科交叉、融合，只有这样，才有可能在时间和空间尺度上阐明土壤组分在环境界面上的复杂反应过程和机理。展开更多
The BL14W1 beamline at Shanghai Synchrotron Radiation Facility(SSRF) is an X-ray absorption finestructure(XAFS) beamline, for investigating atomic local structure, which is demanded extensively in the fields of physic...The BL14W1 beamline at Shanghai Synchrotron Radiation Facility(SSRF) is an X-ray absorption finestructure(XAFS) beamline, for investigating atomic local structure, which is demanded extensively in the fields of physics, chemistry, materials science, environmental science and so on. The beamline is based on a 38-pole wiggler with the maximum magnetic field of 1.2 T. X-rays of 4.5–40 ke V can be extracted by the optical scheme consisting of white beam vertical collimating mirror, liquid-nitrogen-cooled double crystal monochromator of Si(111) and Si(311), toroidal focusing mirror and higher harmonics rejection mirror. The maximum photon flux about 5 × 1012photons/s at the sample at 10 ke V, with a beam size of 0.3 mm × 0.3 mm. The beamline is equipped with four types of detectors for experiments in either transmission or fluorescence mode. At present,quick-XAFS, grazing incidence XAFS, X-ray emission spectroscopy, high-pressure XAFS and time-resolved X-ray excited optical luminescence methods have been developed.展开更多
Copper ion is the essential microelement to many organisms. In this paper, the local structure of Cu2+ in CuBr2 aqueous solutions with different concentrations are investigated by using X-ray absorption fine structure...Copper ion is the essential microelement to many organisms. In this paper, the local structure of Cu2+ in CuBr2 aqueous solutions with different concentrations are investigated by using X-ray absorption fine structure (XAFS) technique. XANES (X-ray Absorption Near Edge Structure) spectra indicate that charge transfer from Br- to Cu2+ decreases with the solution concentration, which lead to a shift of the absorption edge. The shoulder appearing at the rising edge proves to be characteristic of a tetragonal distortion. The Fourier transform magnitudes of EXAFS (Extended X-ray absorption fine structure) data of Cu species suggest that more Cu-Br bonds may exist in high concentrations. A fivefold coordination configuration like a pyramid is used as the fitting parameters. From the analysis of the coordination numbers, the proportion of Cu-O and Cu-Br is 4:1 in the saturated solution. The Br atom is on the equatorial plane of the model. The fitting results agree well with the experiment data.展开更多
ZnO films, doped with 2.9 atom% Cu, were prepared by radio frequency magnetron sputtering on sapphire substrate at different substrate temperatures. No magnetic impurities such as Fe, Co and Ni were found in the PIXE ...ZnO films, doped with 2.9 atom% Cu, were prepared by radio frequency magnetron sputtering on sapphire substrate at different substrate temperatures. No magnetic impurities such as Fe, Co and Ni were found in the PIXE spectra. The ZnO:Cu films possessed the wurtzite ZnO structure. No precipitates such as CuO and Cu2O or Cu cluster, were observed by synchrotron radiation X-ray diffraction in the ZnO:Cu films. Extended X-ray absorption fine structure (EXAFS) analysis showed that Cu atoms were incorporated into ZnO crystal lattice by occupying the sites of Zn atoms.展开更多
X-ray absorption fine structure (XAFS) has experienced a rapid development in the last three decades and has proven to be a powerful structural characterization technique nowadays. In this review, the XAFS basic princ...X-ray absorption fine structure (XAFS) has experienced a rapid development in the last three decades and has proven to be a powerful structural characterization technique nowadays. In this review, the XAFS basic principles including the theory, the data analysis, and the experiments have been introduced in detail. To show its strength as a local structure probe, the XAFS applications in semiconductors are summarized comprehensively, that is, thin films, quantum wells and dots, dilute magnetic semiconductors, and so on. In addition, certain new XAFS-related techniques, such as in-situ XAFS, micro-XAFS, and time-resolved XAFS are also shown.展开更多
文摘由于X射线吸收精细结构（X—rayabsorption fine structure，XAFS）可以原位探测吸收原子的2～3个邻近配位壳层，获得目标元素的电子结构信息和化学结构信息，所以XAFS已成为微观领域最重要的结构分析工具，丰富了我们对元素的重要化学性质和反应过程的认识。本文简述了XAFS的基本原理，探讨了样品制备、测试及数据分析等过程需关注的问题，重点综述了应用XAFS研究土壤重金属和营养元素的形态、土壤固一液界面的反应过程和机理，并指出其应用的局限性和未来发展的前景，旨在推动我国XAFS在土壤科学中的应用。由于土壤中界面反应的复杂性，XAFS应结合其他结构分析技术，结构分析技术应结合宏观数据和计算机模拟，土壤学应与其他学科交叉、融合，只有这样，才有可能在时间和空间尺度上阐明土壤组分在环境界面上的复杂反应过程和机理。
基金supported by the National Natural Science Foundation of China(21373251)Main Direction Program of Knowledge Innovation of Chinese Academy of Sciences,China(KZCX2-EW-307)~~
基金Supported by National Natural Science Foundation of China(Nos.11175244,11275256 and 11179024)
文摘The BL14W1 beamline at Shanghai Synchrotron Radiation Facility(SSRF) is an X-ray absorption finestructure(XAFS) beamline, for investigating atomic local structure, which is demanded extensively in the fields of physics, chemistry, materials science, environmental science and so on. The beamline is based on a 38-pole wiggler with the maximum magnetic field of 1.2 T. X-rays of 4.5–40 ke V can be extracted by the optical scheme consisting of white beam vertical collimating mirror, liquid-nitrogen-cooled double crystal monochromator of Si(111) and Si(311), toroidal focusing mirror and higher harmonics rejection mirror. The maximum photon flux about 5 × 1012photons/s at the sample at 10 ke V, with a beam size of 0.3 mm × 0.3 mm. The beamline is equipped with four types of detectors for experiments in either transmission or fluorescence mode. At present,quick-XAFS, grazing incidence XAFS, X-ray emission spectroscopy, high-pressure XAFS and time-resolved X-ray excited optical luminescence methods have been developed.
基金Supported by National Natural Science Foundation of China (Grant No.11005148,10705046,11135008)National Basic Research Program of China (Grant No. 2010CB934501)+1 种基金Special Presidential Foundation of the Chinese Academy of Science (Grant No. 29)Science and Technology Commission of Shanghai Municipality (Grant No. 11JC1414900)
文摘Copper ion is the essential microelement to many organisms. In this paper, the local structure of Cu2+ in CuBr2 aqueous solutions with different concentrations are investigated by using X-ray absorption fine structure (XAFS) technique. XANES (X-ray Absorption Near Edge Structure) spectra indicate that charge transfer from Br- to Cu2+ decreases with the solution concentration, which lead to a shift of the absorption edge. The shoulder appearing at the rising edge proves to be characteristic of a tetragonal distortion. The Fourier transform magnitudes of EXAFS (Extended X-ray absorption fine structure) data of Cu species suggest that more Cu-Br bonds may exist in high concentrations. A fivefold coordination configuration like a pyramid is used as the fitting parameters. From the analysis of the coordination numbers, the proportion of Cu-O and Cu-Br is 4:1 in the saturated solution. The Br atom is on the equatorial plane of the model. The fitting results agree well with the experiment data.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10775033 and 11075038)support from Shanghai Leading Academic Discipline Project (Project Number: B107)
文摘ZnO films, doped with 2.9 atom% Cu, were prepared by radio frequency magnetron sputtering on sapphire substrate at different substrate temperatures. No magnetic impurities such as Fe, Co and Ni were found in the PIXE spectra. The ZnO:Cu films possessed the wurtzite ZnO structure. No precipitates such as CuO and Cu2O or Cu cluster, were observed by synchrotron radiation X-ray diffraction in the ZnO:Cu films. Extended X-ray absorption fine structure (EXAFS) analysis showed that Cu atoms were incorporated into ZnO crystal lattice by occupying the sites of Zn atoms.
基金Supported by National Natural Science Foundation of China (Grant No. 10375059,10404023)the Cooperation Program between NSRL and BSRF+1 种基金the Innova-tion Program of Chinese Academy of Sciences Specialized Research Fund for the Doctoral Program of Higher Education.
文摘X-ray absorption fine structure (XAFS) has experienced a rapid development in the last three decades and has proven to be a powerful structural characterization technique nowadays. In this review, the XAFS basic principles including the theory, the data analysis, and the experiments have been introduced in detail. To show its strength as a local structure probe, the XAFS applications in semiconductors are summarized comprehensively, that is, thin films, quantum wells and dots, dilute magnetic semiconductors, and so on. In addition, certain new XAFS-related techniques, such as in-situ XAFS, micro-XAFS, and time-resolved XAFS are also shown.
