BaLiF_3∶Ce~(3+)纳米粒子的制备及其光谱特性

BaLiF3属立方钙钛矿型复合氟化物,作为高效闪烁晶体可用于热中子检测[1].由于其能带隙宽,易于实现各种不同价态稀土离子掺杂,可以获得许多可调谐性质,因此它也是比较理想的光学功能材料的基质[2].Ce3+激活的BaLiF3晶体作为紫外发射的短波固体激光材料和光放大材料的研究多有报道[3~5].Ce3+的发射特性强烈依赖于基质晶体结构[6,7].氟化物基质中氧杂质的含量是影响光谱性质的重要因素[8].为了寻找氧含量低、发射波长更短、可调谐范围更宽的激光材料,本工作制备了BaLiF3∶Ce3+纳米晶,获得了一些新的有意义的实验结果.如果将其引入合适的聚合物基体制备出纳米复合体系,有可能为新一代杂化激光材料提供更理想的光学活性组分[9].1实验部分1.1仪器用日本R igaκu D/maxⅡB型X射线衍射仪(XRD)测量样品的晶体结构,辐射源CuKα1(λ=0·154 1 nm);用日本H itachi S-570环境扫描电子显微镜(ESEM)观察样品的形貌和粒径大小;用日立F-4500荧光光谱仪测试样品的激发和发射光谱;用英国VG公司ESCALAB MKⅡX射线电子能谱仪(XPS)检测样品的含氧量.1.2实验过...

Preparation of europium induced conformation-specific anti-calmodulin monoclonal antibody

Monoclonal antibody technique was employed to detect the conformational difference of CaM induced by metal ions. A trivalent europium ion induced conformation-specific anti-calmodulin monoclonal antibody was successfully prepared with europium-saturated calmodulin as antigen.

Hydrothermal synthesis, crystal structure and properties of [HPDA][H(2)PDA](2)[As-2(III)-AsMo8V4O40]center dot 3H(2)O (PDA = propane diamine)

[NH3CH2CH2CH2NH2][NH3CH2CH2CH2NH3](2)[(As2AsMo8V4O40)-As-III-Mo-V-O-IV].3H(2)O was hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction. Crystal data: monoclinic, C2/c, a = 45.375(9) Angstrom, b = 11.774(2) Angstrom, c = 23.438(5) Angstrom, beta = 96.62(3)degrees. X-ray crystallographic study showed that the crystal structure was constructed by bicapped alpha-Keggin fragments [(As2AsMo8V4O40)-As-III-Mo-V-O-IV](5-) polyoxoanion. The title compound had a high catalytic activity for the oxidation of benzaldehyde to benzoic acid using H2O2 as oxidant in a liquid-solid biphase system.

Crystal form transition during heating of solvent-induced crystalline syndiotactic polystyrene

The phase transition of two kinds of solvent-induced crystalline syndiotactic polystyrene (sPS). gamma-sPS and delta(c)-sPS, has been studied via WAXD and DSC. gamma-sPS transform to a-sPS at 195-225 degrees C before melt during heating, whereas delta(e)-sPS transform to first gamma-sPS and then a-sPS at 100-200 degrees C and 200-215 degrees C, respectively. The transition of delta(e)-gamma and gamma-a occurs for below melting point of sPS indicates they are all solid-solid transition.

Photoluminescent properties of organic film in flat optical microcavity

The microcavity is sandwiched between a quarterwavelength distributed Bragg reflector(DBR) and a metal Ag reflective mirror. A single layer of a Tris(8-quinolinolato)aluminum (Alq) film was used as the light-emitting layer. The photoluminescent properties of the optical microcavity and that of the Alq film were studied at the same excitation condition. Compared with the Alq film,the significantly narrowed spectral emission linewidth from 90 nm to 10 nm was observed, the PL emission intensity of the microcavity at the resonant mode is enhanced by the order of 1. The spectral narrowing and intensity enhancement of the microcavity is attributed to the microcavity effect.

Using triazine as coupling unit for intramolecular ferromagnetic coupling of multiradicals

Novel high spin tri-, tetra-, pentaradicals, composed of triazine coupling units and cationic amino radical spin centers (+ . NH) under various configurations and linkages, are predicted from AM1-CI calculations. It is found that for charged planar multiradicals the stability of high spin ground states depends on both the molecular configuration and the number of end groups. Generally, cyclic 1,3-bridged charged multiradicals (S less than or equal to 5/2) possess more stable high spin ground states than their isomers under the branched 1,3,5,-bridged configuration. Therefore, it is suggested that in the design of planar high spin molecules with stable high spin ground states, less end groups and all the supposed spin centers and/or the coupling units should be under the same structural situation. (C) 1999 Elsevier Science B.V. All rights reserved.

A study on the mechanism of the abnormal reduction of Eu3+ -> Eu2+ in Sr2B5O9Cl prepared in air at high temperature

This paper reports a new observation of the abnormal reduction of Eu3+ --> Eu2+ in Sr2B5O9Cl when prepared in air at high temperature. A model based on the nature of substitution defects is proposed to explain this abnormal reduction. Electrons, which reduced the Eu3+ ions, are created by the substitution of cations first and then transferred to the target Eu3+ ions via tetrahedral berate anion groups. Codoping experiments are designed and performed. The results of these experiments support the model proposed. (C) 1999 Academic Press.

Red color filter in an organo-soluble polyamide matrix for liquid crystal displays

A red color filter was laminated from a solution of red color pigment and an organo-soluble polyamide, based on 1,4-bis(3,4-dicarboxyphenoxy) benzene dianhydride (HQDPA) and 2,2'-dimethyl-4,4'-methylene dianiline (DMMDA). The red color filter in a polyamide matrix with negative birefringence plays an important role in twisted nematic liquid crystal displays (TN-LCDs). The red color filter, and also compensation films, extend the viewing angle of LCDs. (C) 1997 Elsevier Science S.A.

VALENCE STATE EQUILIBRIA BETWEEN COBALT AND MANGANESE IONS AND MAGNETIC-PROPERTIES OF LACO0.9MN0.1O3

According to the thermodynamic equilibria between the low spin state Co(III) (t2g6e(g)0) ion and the high spin state Co3+ (t2g4e(g)2) ion and between the cobalt and manganese ions with different valence state and spin state, an approximate semiempirical f

配合物[Li(DME)_3][(t-BuCp)_2Nd(NPh_2)_2]·(1/2)DME的合成及晶体结构

1990年,Schumann,H.等报道了用双(环戊=烯基)稀土甲基化物与二苯胺进行交换反应制得了[Li(THF)_4][Cp_2Sm(NPh_2)_2],并测定了相应配合物镥的结构。但是,到目前为止,类似的轻稀土配合物尚未报道。这里,我们以双(叔丁基环戊二烯基)氯化钛为前体,与等当量的二苯胺基锂反应,制得了阴离子型配合物[Li(DME)_3][(t—BUCP)_2Nd(NPh_2)_2]·1/2DME,并测定了其单晶结构。

含环氧端基酚酞聚芳醚酮E-PEK的合成及表征

由酚酞和4,4′-二氯二苯酮经亲核缩聚制得了一系列不同分子量的含—OK端基的聚醚酮低聚物,将其与环氧氯丙烷反应得到了分子量为1000～8000的含环氧端基聚芳醚酮(E-PEK)。用IR和~1H NMR表征了E-PEK的分子链结构,测定了T_g、溶解性和熔融粘度。研究了E-PEK/DDE体系的固化,固化后树脂的T_(g∞)=183～215℃,与低聚物的初始分子量有关。

浙贝素的结构测定

从浙江产贝母(Fritillaria thunbergii Miq)地上部分分离出一个新的3,7-二氧杂环[3,3,O)辛酮-6类化合物,经光谱(~1HNMR,~(13)CNMR,HRMS,EI-MS)及X-单晶衍射数据的分析,确定其结构为2-(3′,5′-dimethoxy-4′-hydroxyphenyl)-3,7-dioxabicyclo[3,3,O]octan-6-one,定名为浙贝素(zhebeiresinol)。

AMPEROMETRIC GLUCOSE SENSOR WITH FERROCENE AS AN ELECTRON-TRANSFER MEDIATOR

A glucose oxidase (GOD) electrode with ferrocene (Fc) used as an electron transfer mediator has been described. Using Nafion, Fc was modified on a glassy carbon (GC) electrode surface, and glucose oxidase was then immobilized on the Fc-Nafion film, forming a GOD-Fc-Nafion enzyme electrode. The preparation method was quite simple and rapid. The enzyme electrode showed a reversible reaction of the redox couple (Fc+/Fc), used in a biosensor system, displayed a sensitive catalytic current response (response time was less than 20 s) on variation of the glucose concentration, with a wide linear range up to 16 mM and with good repeatability. The enzyme electrode showed almost no deterioration over the course of three weeks. There was little or no interference from electro-active anions, such as ascorbic acid, to the determination of glucose based on Nafion film and lower oxidizing potentials of the enzyme electrode.

双功能有机物修饰电极的修饰层结构对催化细胞色素C的电极反应的影响

用光谱电化学法研究了双功能有机物健那绿的电化学性质。在铂电极上,健那绿发生四步单电子传递过程。在健那绿修饰电极上细胞色素C的直接、非均相电子传递反应是准可逆氧化还原反应,电极反应速率常数K_s=4.17×10~(-4)cm/s。电极表面的修饰方法不同对细胞色素C的电极反应有很大影响。

Eu~(3+):Ln_2O_2S(Ln=Lu,Y,Gd,La)晶体的角重迭参数计算

本文使用角重迭模型(AOM),针对Eu~(3+):Ln_2O_2S(Ln=Lu,Y,Gd,La)晶体系列,在考虑硫和氧两种不同格位的情况下,对f电子的全部四个角重迭参数e_σ、e_π、e_δ和e_φ进行了计算,得到了一些基本规律,即中心离子与配位体之间的共价性大小次序为Lu～Y>Gd>La,并且Ln-O键的共价性要强于Ln-S键.