BaxSr（1—x）TiO3多层膜椭偏光谱研究

用溶胶－凝胶技术在Bi(100）衬底上制备了单层和渐变型多层的BaxSr(1-X)TiO3薄膜，其膜层组分分别为：Ba0.7Sr0.3TiO3,Ba0.8Sr0.2TiO,Ba0.9Sr0.1TiO3,BaTiO3，对生长制备出的多层BaxSr(1-X)TiO3薄膜进行了变角度椭偏光谱测量，通过椭偏光谱解谱分析研究，首次得到了BaxSr(1-X)TiO3多层膜结构不同膜层的膜厚和光学常数，其结果显示：椭偏光谱分析得到的不同膜层的膜厚与卢瑟福背向散射测量得到的结果基本相符；渐变型多层膜中BaTiO3薄膜的折射率比单层BaTiO3薄膜折射率大许多，与体BaTiO3的折射率相接近，这说明渐变型多层膜中BaTiO3薄膜的光学性质与体材料的光学性质接近。     

Immunoelectron localization of mitochondrial F1 factor in cryosections of heart muscle cells

Immunocytochemistry was used to investigate the localization of F1 ATPase in mitochondria of cryosections of adult mouse heart muscle cells. The initial aldehyde fixation was the only denaturation step for antigens. The fine structure was preserved with contrast enhancement as the sections were maintained hydrated, with the advantage that the entire procedure is completed in one working day. The reaction was highly specific, and entire mitochondria were labeled with the Protein A-gold complex. A new analytical technique, electron spectroscopic imaging (ESI), contributed to a better visualization of the localization of the F1 factor.     

In-situ monitoring and control for MOCVD growth of AlGaAs and InGaAs

We have used spectroscopic ellipsometry to perform real-time monitoring during metalorganic chemical vapor deposition growth of AlGaAs (on GaAs) and InGaAs (on GaAs and InP). Optical constants for these materials were obtained up to growth temperatures of 600 to 700°C. This information permits real-time extraction of composition and layer thickness from the raw ellipsometric data at sample rates on the order of 0.5 Hz. We describe closed-loop control of composition and total layer thickness on AlGaAs-based structures, including Bragg reflectors. In-situ data obtained on double-heterostructure quantum-well laser structures demonstrate that spectroscopic ellipsometry is an extremely powerful monitoring and quality-control tool, giving important real-time information on complex structures that would be difficult and time-consuming to obtain after growth.     

Influence of zero-loss filtering on electron optical phase contrast

Complex scattering amplitudes are used to calculate the phase contrast of colloidal gold particles. Comparison of measurements of the phase contrast intensity at the centre of the gold particle as a function of defocus for unfiltered and zero-loss filtered images demonstrates the increase in phase contrast achieved by zero-loss filtering even for a thick carbon substrate film. The granulation of amorphous germanium films is measured by the spatial rms (root mean square) values of image intensity in a defocus series.     

Monitoring of CdTe atomic layer epitaxy using in-situ spectroscopic ellipsometry

Atomic layer epitaxy or ALE has proven to be useful for the growth of epitaxial layers of high uniformity, good quality, and well-controlled thickness. In this study, we have carried out in-situ monitoring during the atmospheric pressure ALE of CdTe on GaAs (100) substrates using spectroscopic ellipsometry (SE). The susceptor temperature, reactant partial pressures, as well as the flow and flush duration for each precursor are crucial process variables for ALE growth. Growth was carried out for 20–25 cycles under different sets of these process conditions during the experiment and in-situ SE was used to verify the presence of layer-by-layer growth, which enabled the quick determination of the process window. We observed ALE growth of CdTe at 300°C, supporting the explanation that the growth of CdTe occurs via a surface catalyzed decomposition of the Te precursor di-isopropyltelluride (DIPTe). Investigation of ALE mode growth behavior for different susceptor temperatures and DIPTe flush times indicated that the growth was limited by competition between desorption and reaction of the adsorbed DIPTe species on the Cd terminated surface.     

钼酸盐对碳钢缓蚀作用机理的椭圆法研究

用椭圆法通过测定表面膜层厚度,折射系数和表面复盖度研究了钼酸盐对碳钢在工业冷却水中的缓蚀作用。实验结果表明:形成具有良好保护性能的较完整致密的表面膜层的最佳钼酸盐浓度为200ppm。文中对缓蚀作用机理进行了讨论。     

超薄MOF纳米片前驱体高效电催化OER反应

金属-有机骨架材料作为前驱体制备特定形貌的纳米材料用于水氧化反应(OER)，成为新的研究热点。使用溶剂热法在泡沫镍基底上合成超薄的NiCoFe-MOF纳米片，在保留其纳米片形貌的基础上原位电化学转化为金属氢（羟基）氧化物。在1 M KOH电解液中，10 mA?cm-2电流密度时的过电位仅为189 mV，Tafel斜率为35 mV/dec，且长时间电解实验表明其具有较高稳定性。原位拉曼结果表明，反应的高活性来源于反应过程中的“活性氧物种”中间体。     

Adhesion and Hydrolytic Stability of the Interface Between High-Modulus Polyethylene Fibers and Acrylic Resins

The effects of oxyen plasma treatment on the surface chemistry of Spectra 1000® high modulus polyethylene fibers and on the mechanical properties of fiber-reinforced composites of the fibers in a Bis-GMA based acrylic resin have been studied. X-ray photoelectron spectroscopy and diffuse reflectance FTIR spectroscopy have been used to show that the majority of oxygen on the fiber surface exists mostly in the form of ether and/or epoxy linkages, with carbonyl-, carboxylic- and ester-containing compounds accounting for less than 10 percent of the total. While the untreated and plasma-treated fibers have similar chemical compositions, the surfaces of the plasma-treated fibers are more polar and the oxygen is chemically bonded instead of being merely physisorbed. The interfacial shear strength between the fibers and the acrylic resin is increased by a factor of 2.3 by the plasma treatment indicating the presence of a weak boundary layer on the surface of the untreated fibers. The hydrolytic stability of the composite interfaces was investigated for fibers sized with several Bis-GMA-based adhesives. Maximum stability was attained by sizing with Bis-GMA containing a peroxide catalyst or an amine accelerator. The flexural properties of composites utilizing plasma-treated and untreated fibers were compared in three-point bending. The ultimate bending loads for composites using treated fibers were much higher than those for composites with untreated fibers, but only a fraction of that for glass or Kevlar®-reinforced materials.     

In situ ellipsometric study of a palladium catalyst during the oxidation of methane

Ellipsometry is used to follow the growth of a PdO layer on the surface of a thick Pd-film catalyst during methane oxidation at 500°C. The oxide layer that develops under rich conditions (excess CH₄) is quite porous and roughens with time. Little CO is formed during this period, but the CO₂ formation rate increases until spontaneous oscillations develop, which correlate with changes in the ellipsometric data. These changes indicate that the porous oxide rapidly converts to a metal-rich state, which has decreased catalytic activity, and then slowly reoxidizes.     

Synthesis and metal uptake studies on poly(8‐hydroxy‐5‐azoquinolinephenylacrylate‐formaldehyde) resin and its metal complexes

8‐hydroxy‐5‐azoquinolinephenylacrylate‐formaldehyde (8H5AQPA‐F) macromonomer was prepared from acryloylchloride, with condensation products of 8‐hydroxy‐5‐azoquinolinephenol‐formaldehyde, and polymerized in DMF at 70°C using benzoyl peroxide as free radical initiator. Poly(8H5AQPA‐F) was characterized by infrared and nuclear magnetic resonance spectroscopic techniques. Polychelates were obtained in alkaline solution of polymeric ligand, with the aqueous solution of Cu(II) and Ni(II). Elemental analysis of polychelates suggests that the metal to ligand ratio is about 1:2. The polymer metal complexes were also characterized by IR, XRD, magnetic moments, and thermal analysis. The effects of pH and electrolyte on the metal uptake behavior of the resin were also studied. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 797–802, 2007