SYNTHESES OF METHYLCYCLOPENTADIENYL DERIVATIVES OF LANTHANIDES (LN = LA-ND) AND CRYSTAL-STRUCTURES OF [(THF)2LI(MU-CL)2]2[MECPND(THF)] AND [LI(DME)3][MECPLA(NPH2)3]

The reaction of LnCl3.2LiCl with 1 equiv of MeCpNa in THF gives the complexes [(THF)2Li(mu-Cl)2]2[MeCpLn(THF)] (Ln = Nd (1), La (2)) in good yield. These precursors react further with 2 equiv of LiNPh2 to produce the new complexes [Li(DME)3][MeCpLn(NPh2)3] (Ln = La (3), Pr (4), Nd (5)). They have been characterized by elemental analyses and IR and NMR spectra, as well as by structural analyses of 1 and 3. The chloride 1 crystallizes in the monoclinic space group P2(1)/n (No. 14) with a = 12.130 (5) angstrom, b = 17.343 (5) angstrom, c = 17.016 (5) angstrom, beta = 108.54 (3)-degrees, V = 3393.87 angstrom3, Z = 4, and D(c) = 1.45 g/cm3. Least-squares refinement led to a final R value of 0.051 (I greater-than-or-equal-to 3-sigma(I(o))) for 2004 independent reflections. Complex 3 crystallizes in the monoclinic space group P2(1)/c (No. 14) with a = 18.335 (6) angstrom, b = 16.576 (5) angstrom, c = 17.461 (6) angstrom, beta = 96.04 (3)-degrees, V = 5277.17 angstrom3, D(c) = 1.26 g/cm3, Z = 4, and R = 0.057 (I greater-than-or-equal-to 2.5-sigma(I(o))) for 3378 reflections. The structure of 3 consists of discrete ion pairs [Li(DME)3]+ and [MeCpLa(NPh2)3]- with average La-N and La-C(ring) distances of 2.459 (8) and 2.84 (1) angstrom, respectively.

ELECTROCHEMICAL-BEHAVIOR OF YTTRIUM ION IN LICL-KCL-NACL EUTECTIC MELT

The electrochemical reduction of yttrium ion on a molybdenum electrode in a LiCl-KCl-NaCl eutectic melt at 723 K was found to be almost reversible and to proceed by a one-step three electron reaction. The diffusion coefficient D of the Y(III) ion was measured to be (3.3 +/- 0.4) x 10(-6) cm2 s-1 by cyclic voltammetry, (5.0 +/- 0.9) x 10(-6) cm2 s-1 by the rotating disk electrode method, and (7.1 +/- 0.7) x 10(-6) cm2 s-1 by chronopotentiometry. The D values obtained by the latter two methods are in fairly good agreement with each other. The rather low D value obtained by cyclic voltammetry might be attributed to the fact that yttrium metal can dissolve slightly in the chloride melt. The standard potential of Y(III)/Y(0) couple was determined to be (-3.174 +/- 0.006) V (vs. Cl2/Cl-) by open-circuit potentiometry, (-3.15 +/- 0.02) V (vs. Cl2/Cl-) by the rotating disk electrode method and (-3.16 +/- 0.02) V (vs. Cl2/Cl) by chronopotentiometry. These three values are in good agreement with each other. Several types of Ni-Y intermetallic compounds were found to be formed on a nickel electrode.

RELATIONSHIP BETWEEN CRYSTALLIZATION OF THE PDMS BLOCK AND MORPHOLOGY OF POLY(BUTADIENE-B-DIMETHYLSILOXANE)

Studies using transmission electron microscopy, differential scanning calorimetry, and X-ray diffraction showed correlations between the crystallization behavior of the polydimethylsiloxane (PDMS) block and the morphology of the block copolymer poly (butadiene-b-dimethylsiloxane) (PB-PDMS). When the PDMS component existed as spheres dispersed in a PB matrix, the crystallization rate of the PDMS block was lower than when the PDMS phase existed in rod or cylinder form.

NATURAL RADIATIVE LIFETIMES OF THE EXCITED-LEVELS OF THULIUM

The radiative lifetimes of eight excited levels of thulium have been measured with the method of stepwise excitation from the 4f13(F-degrees-7/2)6s2(1S0)\7/2\ ground state to the states studied using two pulsed dye lasers. Optical transients were recorded through observing fluorescences and evaluated with regard to the decay time. The accuracy of the measured lifetime values is about 10%.

DYNAMIC SCALING AND FRACTAL BEHAVIOR OF SPINODAL PHASE-SEPARATION IN POLYMER MIXTURES OF POLY(METHYL METHACRYLATE) WITH POLY(STYRENE-CO-ACRYLONITRILE)

Dynamic scaling and fractal behaviour of spinodal phase separation is studied in a binary polymer mixture of poly(methyl methacrylate) (PMMA) and poly(styrene-co-acrylonitrile) (SAN). In the later stages of spinodal phase separation, a simple dynamic scaling law was found for the scattering function S(q,t):S(q,t) approximately q(m)-3S approximately (q/q(m)). The possibility of using fractal theory to describe the complex morphology of spinodal phase separation is discussed. In phase separation, morphology exhibits strong self-similarity. The two-dimensional image obtained by optical microscopy can be analysed within the framework of fractal concepts. The results give a fractal dimension of 1.64. This implies that the fractal structure may be the reason for the dynamic scaling behaviour of the structure function.

十六烷基三甲基溴化铵水溶液热致相变的红外光谱研究

在280～320K的温度范围内考察了30％十六烷基三甲基溴化铵水溶液的红外光谱随温度的变化。结果表明该体系的凝聚胶-液晶相转变温度为300K。在300K以下的凝聚胶相,分子的极性头部基团处于高度“固定”的状态,分子的碳氢链以有序的相互平行方式排列,极性头与碳氢链之间有一定的倾斜角。在300K以上的液晶相,极性头内部CH_3-(N~+)基团以及整个极性头与碳氢链之间发生了旋转,碳氢链变为以六方亚晶胞填充形式存在,旦扭曲式构象异构体数量显著增多,极性头与碳氢链之间已不存在倾斜角,分子的亲水极性头和疏水碳氢链部分都处于“融化”状态。

高纯氧化铒中镨、钐、镝、钬、铥和钇的电感耦合等离子体原子发射光谱分析

本文采用PGS-2型2米平面光栅光谱仪和ICP光源联用,样品溶液以乙醇预去溶方式引入ICP,直接同时测定了高纯氧化铒中6个痕量稀土杂质。当样品溶液中Er_2O_3的浓度为5mg/ml时,测定下限为镨和钐为0.0010％,镝、钬、和铥为0.0020％,钇为0.00080％。分析结果令人满意,其相对标准偏差为4.4～6.8％。

用自动元素分析仪测定含氟化合物中的碳、氢

本文介绍用兰州化物所制备的Ag_2WO_4,MgO/AgVO_3催化剂分析含氟量很高的高分子化合物中的碳、氢的方法。该法的优点是快速、简便、燃烧温度低。测定的绝对误差不大于0.3%。 2 仪器和试剂: Carlo Erba 1106型元素分析仪,精度为lμg的天平,锡箔压制的样品小舟。Ag_2WO_4,MgO/AgVO_3兰州化物所制,镀银还原铜自制。氧气、氦气的纯度为99.999％。

二甲苯异构体双电荷离子和单电荷离子的动能谱研究

利用质量分析离子动能谱和碰撞诱导解离技采研究了邻、间、对二甲苯分子在电子轰击质谱中产生的双电荷离子[C8H10]2+、[C8H9]2+和单电荷离子[C8H10]+。根据测定的电荷分离反应的释放动能T和由此估算的双电荷离子电荷分离反应过渡态两电荷间距R,推测出过渡态的结构,利用单电荷离子[C8H10]+的MIKES/CID谱可区分邻二甲苯与间、对二甲苯异构体.

稀土对LF_(21)铝合金电解着色层耐蚀性能的影响

通过添加富铈(含量为52％的)混合稀土,考察了不同混合稀土加入量,不同的氧化着色工艺及其它因素对稀土铝锰合金膜层耐蚀性能影响。结果表明:稀土元素明显地改善和提高电解着色层的耐紫外线、耐热、耐水、耐酸、碱盐及各种气体等腐蚀性能。

铥原子中等能量能级自然辐射寿命的时间分辨荧光测量

报道铥(Tm)原子10个中等能量激发能级自然辐射寿命的实验测量值.采用两台脉冲染料激光器将铥原子从基态激发到待测能级,再从铥原子激发态所释放的荧光随时间衰变的规律推算出自然辐射寿命值.测量精确度为10％.

双色三光子共振电离测量钐原子高激发态4f~6s7S新能级

本文报道用双色三光子共振电离法测量钐原子高激发态78个新能级。这些新测定的偶宇称能级属于4f~66s7S电子构型,位于33477～37758cm~(-1)能量范围。