Pr1—xSrxMnO3体系价带的光电子能谱研究

对于x从0．0到0．4之间变化的Pt1-xSrxMnO3多晶体所进行的价带光电子能谱实验显示，在Fermi边和Fermi边以下－12eV范围内出现的能带态密度随掺杂量x有一个显的变化。对这些现象以Pr1-xSrxMnO3体系在基态下发生电荷转移为出发点进行了讨论。提出了随掺杂量x的非线性电荷转移机制和存在由电荷转移导致的二级相变的可能性。     

SiTi1—xSbxO3透明导电薄膜的光电子能谱研究

我们用XPS和同步辐射技术研究了钙钛矿型氧化物SrTi1-xSbxO3(x=0,0.05,0.10,0.15,0.20）薄膜的电子结构。该薄膜系列在可见光波段透明,其透过率均超过90％。所有掺杂薄膜均导电。同步辐射电子能谱研究结果表明该薄膜中来自Sb杂质的退局域化电子在母化合物的禁带中引入了杂质能级。这是导电性的根源,价带中很小的电子态密度限制了跃迁几率。大的禁带宽度和小的跃迁几率是光学透明性的原因。     

葡聚糖修饰Fe_3O_4磁性纳米粒子的同步辐射光电子能谱研究

在纳米Fe3O4表面修饰葡聚糖可在粒子表面建立空间位阻稳定层,不仅提高了纳米粒子在水中的分散稳定性,还增强了纳米粒子的生物相容性.本文在柠檬酸钠介质中合成了葡聚糖修饰的Fe3O4纳米粒子,采用同步辐射X射线光电子能谱(XPS)对未经修饰和葡聚糖修饰后的Fe3O4纳米粒子表面的化学组分、表面原子的化学结构、化学键合情况进行了定性和定量分析,并给出葡聚糖修饰Fe3O4纳米粒子的反应机理.结果表明,反应体系中的柠檬酸钠首先在Fe-O-C键包覆到Fe3O4纳米粒子表面,然后葡聚糖分子与纳米粒子外的COO-以氢键结合并同时发生葡聚糖大分子缠绕包裹连接到纳米粒子表面,这大大增强了反应体系的分散稳定性和葡聚糖修饰氧化铁纳米粒子的亲水性.     

聚乙烯醇修饰Fe3O4纳米颗粒的制备表征及同步辐射X射线光电子能谱研究

采用水溶性高分子聚合物聚乙烯醇(PVA)对Fe3O4纳米颗粒表面进行功能化修饰,利用透射电镜(TEM)、紫外可见吸收光谱(UV-vis)、Zeta电位检测、电感耦合等离子体质谱(ICP-MS)和热重分析(TGA),对包被前后Fe3O4的粒径、分散稳定性、PVA的包覆效率及纳米颗粒进入细胞的量进行了表征研究.通过同步辐射...     

八氧化三铀的X射线光电子能谱研究

用Ｘ射线光电子能谱分析研究了八氧化三铀的表面结构以及一氧化碳对Ｕ３Ｏ８表面结构的影响，Ｕ３Ｏ８为混合价比合物，ＸＰＳ分析表明它符合Ｕ２＾ⅥＵｎ－２＾ⅥＯ２ｎ＋２模式。同时ＵＯ３的量减少了１６％，研究结果表明一氧化碳气氛对Ｕ３Ｏ８的表面有一定的还原作用。     

NSRL光电子能谱站控制系统改造及软件设计

为了适应同步辐射应用技术发展的需要，我们对合肥国家同步辐射实验室（NSRL）光电子能谱站的数据采集和控制系统的硬件和软件进行了履行，取得了预期的效果。硬件系统方面，增加了一组多功能卡，更换了这控制器，增加了光子能量反馈系统；与之相应的软件得以重写，同时，对软件自身也进行了完善，增加了参数存取功能，修改了数据存储格式，并加入XPS工作模式。通过测量一组Ni的费米边的EDC（Energy Distribution Curve）实验曲线测试了整个系统的工作情况。     

Crystal structure determination of a chimeric FabF by XRD

Beta-ketoacyl-acyl-carrier-protein synthase Ⅱ,an important enzyme in biosynthesis of bacterial fatty acid,is an attractive target in antibacterial drug design. Platensimycin(PTM), produced by Streptomyces platensis, has a strong, broad-spectrum Gram-positive antibacterial activity by selectively targeting to Fab F but exhibits no inhibition to the Fab F from Streptomyces platensis(spFabF). To study the self-resistance mechanism within the PTM-producing strain and provide hint for development of novel antibiotics, it is imperative to solve the structure of spFabF and elucidate the difference between spFabF and other Fab Fs which are not resistant to PTM. To this end, we constructed four chimeric Fab Fs based on the sequence of spFabF and its homologous protein after the expression of wide-type spFabF was failed. The crystal structure of one chimera, js_(200)FabF, of 91.2% sequence identity to spFabF,was solved. A structure comparison of js_(200)FabF with a PTM-bound Fab F suggested that three loops nearby the catalytic site might play key roles in preventing the binding of PTM to spFabF. The results provide an encouraging basis for further studies on the self-resistance mechanismand structure-based design of novel antibiotics targeting FabFs.     

X射线吸收光谱技术中的滤光片研制

在同步辐射X射线吸收光谱(XAS)实验中,X射线滤光片用于吸收样品的康普顿散射和弹性散射,改善荧光信号的质量。我们将ZnO颗粒分散在聚氨酯溶液里,通过恰当的喷涂工艺,获得ZnO滤片。X射线衍射(XRD),X射线荧光(XRF)及X射线吸收光谱(XAS)实验结果表明：在滤片制备过程中,ZnO结构保持不变。进一步地,ZnO滤片用于测量Ga2O3的GaK边XAS谱,显示出好的信噪比。采用同样的方法还制备了其它X射线滤光片,表明这种X射线滤光片制备技术的可行性和实用性。     

hPRS1蛋白酶的同步辐射真空紫外圆二色光谱研究

人的PRPP合成酶1(hPRS1:Human phosphoribosylpyrophosphate synthetase)是与人体核苷酸代谢途径密切相关的一种重要合成酶.本文利用同步辐射真空紫外圆二色光谱(SRCD)实验方法研究hPRS1二级结构特征,以及通过添加反应底物,观察hPRS1二级结构的变化.研究发现,在添加相应底物的条件下,显示出hPRS1二级结构富有弹性,在外界因素发生改变时,二级结构相应发生较大变化,这个结果表明hPRS1蛋白二级结构的改变对于发挥功能作用是必需的.     

Studies of multilayer structure in depth direction by soft X-ray spectroscopy

1 Introduction Over the recent several decades, artificial layered structures have been extensively developed as useful functional structures for semiconductor devices [1], magnetic devices [2], X-ray high-reflectance mirrors [3], and so on. They are initially designed as multilayers consisting of uniform layers with the same properties as those of bulk materials and having clear-cut inter- faces (boundaries). However, in real cases, some lay- ers have structures different from those of bulk m…     

气相纯化处理对碳纳米管修饰的XANES和XPS谱学研究

结合X射线近边吸收谱和光电子能谱对经过一系列纯化过程处理后的单壁碳纳米管进行系统的表征.这些纯化过程包括空气氧化、盐酸浸泡以及退火处理.从实验结果发现单壁碳纳米管的表面修饰程度在纯化过程中逐渐增强,经过Ar气保护下的高温退火后,这些表面修饰明显减少.同时还发现单壁碳纳米管能与氯原子成键,这种简单的修饰方法可能对单壁碳纳米管的应用具有重要意义.     

Examination of U valence states in the brannerite structure by near-infrared diffuse reflectance and X-ray photoelectron spectroscopies

The valence state of uranium doped into a f⁰ thorium analog of brannerite (i.e., thorutite) has been examined using near-infrared (NIR) diffuse reflectance (DRS) and X-ray photoelectron (XPS) spectroscopies. NIR transitions of U⁴⁺, which are not observed in spectra of brannerite, have been detected in the samples of U_xTh_1−xTi₂O₆, and we propose that strong specular reflectance is responsible for the lack of U⁴⁺ features in UTi₂O₆. Characteristic U⁵⁺ bands have been identified in samples in which sufficient Ca²⁺ has been added to nominally effect complete oxidation to U⁵⁺. XPS results support the assignments of U⁴⁺ and U⁵⁺ by DRS. The presence of residual U⁴⁺ bands in the spectra of the Ca-doped samples is consistent with segregation of Ca²⁺ to the grain boundaries during high temperature sintering.     

Influence on electron energy loss spectroscopy of the niobium-substituted uranium atom: A density functional theory study

We present the electronic structure and electron energy loss spectroscopy (EELS) for uranium, niobium and U3Nb in which uranium is substituted by niobium. Comparing the electronic structures and optical properties for uranium, niobium and U3Nb, we found that when niobium atom replaces uranium atom in the center lattice, density of state (DOS) of U3Nb shifts downward to low energy. Niobium affects DOS forfand d electrons more than that for p and s electrons. U3Nb is similar to uranium for the electronic energy loss spectra.