Photochemistry of f-element ions

Published data on photochemical reactions of f-element compounds, namely, uranyl ion and lanthanide and actinide ions, are surveyed and analyzed. The types of reactions of photoexcited ions, reaction mechanisms, and analytical applications of the photochemical methods for the separation, isolation, and determination of f-elements are considered.     

Studies on Non-isothermal Kinetics of the Thermal Decomposition of Eu2(BA)6(bipy)2

The thermal decomposition of Eu₂(BA)₆(bipy)₂ (BA=C₂H₅N^– ₂, benzoate; bipy=C₁₀H₈N₂, 2,2'-bipyridine)and its kinetics were studied under the non-isothermal condition by TG-DTG, IR and SEM methods. The kinetic parameters were obtained from analysis of the TG-DTG curves by the Achar method, the Madhusudanan-Krishnan-Ninan (MKN) method, the Ozawa method and the Kissinger method. The most probable mechanism function was suggested by comparing the kinetic parameters. The kinetic equation for the first stage can be expressed as: dα/dt=Aexp(–E/RT)3(1–α)^2/3. This revised version was published online in August 2006 with corrections to the Cover Date.     

冠醚取代蒽醌超分子体系的设计与合成及分子内能量转移的研究

大环冠醚由于其自组装性能及分子识别能力而引起人们广泛的重视.近来,冠醚又成为在超分子体系中用于建构主体分子的一种重要的建造单元^[1~4].Costa^[5]等曾报道苯并冠醚与被识别的稀土离子铕(Ⅲ)与铽(Ⅲ)之间的能量传递过程,选择性激发冠醚主体观察到稀土离子的发光.由于二氮杂冠醚与稀土离子能形成更稳定的配合物^[6].我们利用了冠醚分子的分子识别能力及蒽醌分子的光敏性,设计合成了一种新的氮杂冠醚取代蒽醌分子(图1)(以下文中用代号AQ-CW表示),并以该分子作为主体分子,以稀土离子作为客体构成超分子体系,研究超分子体系内的能量转移过程.     

Photoreduction of Europium (III) in Sol-Gel Derived Inorganic-Organic Hybrid Materials

Eu²⁺-doped inorganic-organic hybrid materials, which are potentially suitable for a tunable laser in the near ultra violet and blue region, were prepared through the photoreduction of Eu³⁺ ions in the materials under the irradiation of the fourth harmonic wave light (266 nm) of the Nd:YAG laser. The hybrid materials doped with Eu³⁺ ions were prepared from Si(OCH₃)₄, CH₃Si(OCH₃)₃, EuCl₃ and chloropropyltrimethoxysilane (CPTM). After the prehydrolized silica sol was added to the Eu³⁺-containing solution, Eu³⁺-doped transparent inorganic-organic hybrid material was obtained by drying at 50°C. The emission peak around 450–475 nm due to the charge transfer transition (5d-4f) of Eu²⁺ ions increased with the laser irradiation time. Eu³⁺ ions were effectively photoreduced to Eu²⁺ ions in pore-free materials prepared at high CPTM to Eu³⁺ ratios. Eu²⁺ ions were generated by the photodecomposition of the bond between Eu³⁺ and Cl (Cl^– or Cl(CH₂)₃ in CPTM).     

铕-二茂铁衍生物配合物修饰电极的电化学行为

研究了影响铕 二茂铁衍生物配合物薄膜修饰电极伏安性质的各种因素 ,讨论了薄膜电极的电荷传递过程。在LiClO4 和甘氨酸底液中 ,在 0～ 0 8V(vs.SCE)电位范围内可观察到修饰电极的氧化还原峰 ,薄膜修饰电极在底液中是一种薄层扩散过程 ,用计时库仑法测得其表观扩散系数为 2 1× 1 0 - 10 cm2 ·s- 1。溶液平衡离子的水合半径大小、离子强度、溶剂对薄膜的溶胀性质以及薄膜的厚度是影响薄膜修饰电极伏安性质的主要因素。同时测定了电极反应的表观速率常数ks 为 6 7× 1 0 - 1s- 1。     

XANES at Eu-L3 edge and valence of europium in SrB_4O_7: Eu and BaB_8O_(13): Eu

The luminescent materials SrB4O7: Eu and BaB8O13: Eu were synthesized, and the valence states of europium in the materials were measured by means of XANES at Eu-L3 edge. It is found that the Eu3 and Eu2 ions are all present in the materials, and more Eu3 ions can be reduced in SrB4O7: Eu than in BaB8O13:Eu. The excitation and emission spectra of Eu3 in SrB4O7: Eu and BaB8O13:Eu were determined.     

掺稀土元素Eu的MgSO4热释发光谱研究

研制了CaSO4:Eu和MgSO4:Eu磷光体,测量了^60Coγ射线辐照后的热释光三维发光谱。测得CaSO4:Eu发光谱中有一个峰温为144℃,波长在390nm处Eu^2 离子能级跃迁产生的主发光峰。MgSO4:Eu同样有一个Eu^2 离子产生的主发光峰,峰温在146℃。但波长在440nm。同时还观测到Eu^3 的能级跃迁产生的波长为590nm和620nm,峰温约在145℃,190℃,260℃和360℃的4个强度较弱的发光峰。它们的峰值分布与MgSO4:Dy的发光峰基本相同。结果表明,Eu^3 在不同硫酸盐中发光谱波长基本相同,而Eu^2 离子在不同硫酸盐中发光谱的波长与该材料的阳离子半径成反比。     

水溶液中新型氨羧螯合剂对Eu3+、Tb3+离子的敏化发光性能研究

研究了四种新型氨羧螯合剂在水溶液中自身的荧光及对Eu3+、Tb3+离子的敏化发光性能.考察了浓度、pH值对荧光强度的影响.     

超薄EuF_3电极修饰层对有机场效应晶体管性能的提升

采用EuF3薄层修饰低功函数金属Ag源、漏电极,制备了CuPc有机场效应晶体管,研究了不同厚度EuF3对器件性能的影响。结果表明,EuF3的厚度由0 nm增至0.6 nm时,接触电阻由23.65×105Ω·cm减至3.86×105Ω·cm,使得器件载流子迁移率由1.5×10-3cm2·V-1·s-1提高到4.65×10-3cm2·V-1·s-1。UPS测试结果表明,薄层EuF3在Ag与有机半导体间形成了界面偶极势垒,使源漏电极表面功函数增大,空穴注入势垒降低,Ag电极与有机半导体层界面的接触电阻减小,进而提升了空穴的注入效率。     

含稀土铕(Ⅲ)配位聚合物的研究

将铕的有机配合物NaEu(TTA)4与聚（苯乙烯-丙烯酸）（PSAA）反应制备了铕配位聚合物[Eu(Ⅲ）-TTA-PSAA]，用电导、DTA-TGA、荧光光谱等对其进行了表征。由于配合物中存在着Eu^3 分别与TTA^-和PSAA分子中羧基的配位作用，并进一步交联，因此配合物样品均不溶于大部分有机溶剂，只能溶于N，N-二甲基甲酰胺和丙三醇/异丙醇的混合溶剂，且耐热性得到提高。配合物为褐色固体，在常温、紫外光下发出红光，主要是由于Eu^3 离子的^5D0→^7F2跃进。讨论了pH值对配合物荧光强度的影响，当pH=10时，合成的配合物具有最好的荧光性。