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A VUV beamline at the Shanghai Synchrotron Radiation Facility (SSRF) for angle-resolved photoelectron spectroscopy (ARPES) measurements is designed. To increase the resolution and bulk sensitivity, a photon energy as low as 7 eV is desired. Because the reflectivity for p-polarized photons strongly decreases when the photon energy is below 30 eV, the design of a high flux beamline for low energy VUV photons is a challenge. This work shows a variable including angle Varied Line-space Plane-Grating Monochromator (VLPGM) with varied grating depth (VGD) which can achieve both high resolution and high flux with broad energy coverage.  相似文献   
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 1.什么是EXAFS?自1895年伦琴发现X射线以来,X射线已被广泛应用于物质结构分析中.我们知道,原子核外电子所具有的能量是量子化的,即只能处于一些分离的能级.我们依次定义这些能级为K、L、M……能级.假设有一束单色X光入射到一片铜箔上.逐渐提高入射光子的能量,当达到铜原子的某个能级的能量时,光子就会被铜原子共振吸收,形成吸收系数的突变.我们称这种突变为吸收边.  相似文献   
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All commercial electron spin polarimeters work in single channel mode, which is the bottleneck of researches by spin-resolved photoelectron spectroscopy. By adopting the time inversion antisymmetry of the magnetic field, we developed a multichannel spin polarimeter based on normal incident very low energy electron diffraction (VLEED). The key point to achieve the multi-channel measurements is the spatial resolution of the electron optics. The test of the electron optics shows that the designed spatial resolution can be achieved and an image type spin polarimeter with 100 times 100, totally ten thousand channels is possible to be realized.  相似文献   
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不同焙烧温度对Cu/γ-Al2O3催化剂铜物种结构的影响   总被引:7,自引:1,他引:6  
用XRD和EXAFS研究了焙烧温度(35─1000 ℃)和负载量(质量分数为5-15%Cu)对于Cu/γ-Al_2O_3催化剂铜物种的影响。低于700 ℃焙烧时,铜以高分散状态存在。根据Cu~(2+)同时占据八面体(Oh)和四面体(Td)两种位置,对第一壳层的Cu-O配位峰进行了拟合。结果显示,随着焙烧温度增加,铜氧配位距离逐渐增加,Cu~(2+)(Oh)/Cu~(2+)(Td)的比例降低,并且Cu~(2+)(Oh)与氧的平均配位数从5.1变成6.0.这表明Cu~(2+)离子由Oh位向Td位迁移,同时向内层扩散使表面配位不饱和的氧缺顶畸变八面体部分变为配位饱和的对称八面体。900 ℃和更高温度的焙烧,使铜离子扩散进载体相形成CuAl_2O_4。  相似文献   
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乔山  冼鼎昌 《中国物理 C》1992,16(7):582-587
本文报道了在北京同步辐射实验室4W1B光束线双晶单色器的安装调试过程中所做的理论计算.给出了单色光强度、能量分辨率及能量的准确性与各个可调整自由度的关系.由计算结果,提出了合理的双晶单色器调整步骤及各个自由度的调整精度要求.  相似文献   
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Seeking new order parameters and the related broken symmetry and studying their relationship with phase transition have been important topics in condensed matter physics. Here, by using spin-and angle-resolved photoemission spectroscopy, we confirm the helical spin texture caused by spin-layer locking in the nodal region in the cuprate superconductor Bi2Sr2CaCu2O8+δ and discover the anisotropy of spin polarizations at nodes along Γ –X and Γ –Y directio...  相似文献   
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