胺三乙酸银晶体和分子结构的测定

(CH₂COOH)₂NCH₂COOAg属于单斜晶系,单位晶胞中包含有四个分子,晶胞周期为α=7.61₁?,b=4.98₄?,c=23.25?,β=104°52′。空间羣为P2₁/c(C_2h⁵)。用柏特森及电子密度函数方法获得了原子坐标。键长C—C=1.51?,N—C=1.48?,C—O=1.28?及Ag—O=2.23—2.73?。指出了在分子之间具有较强的氢键O…O=2.54?。     

Mn3O4包覆对LiNi0.5Mn1.5O4正极材料界面电化学性能的提高

本文采用化学湿磨法，首次将金属氧化物Mn₃O₄包覆于LiNi_0.5Mn_1.5O₄颗粒表面，使得电极材料的电子电导率从1.53×10^-7 S/cm 提高到3.15×10^-5 S/cm. 电化学测试结果表明Mn₃O₄包覆大大提高LiNi_0.5Mn_1.5O₄正极材料的倍率性能和高温循环稳定性. 最佳包覆样品为2.6wt% Mn₃O₄包覆的LiNi_0.5Mn_1.5O₄，在10 C倍率下具有108 mAh/g的高放电容并且在55 °C下100次循环后仍有78%的容量保持率，远大于未包覆样品67%的容量保持率.     

CH3OH在ZnO(0001)表面的光催化解离

本文利用266 nm波长的激光及程序升温脱附的方法研究了甲醇在ZnO(0001)表面的光催化反应. TPD结果显示部分的CH₃OH以分子的形式吸附在ZnO(0001)表面,而另外一部分在表面发生了解离. 实验过程中探测到H₂,CH₃^·,H₂O,CO,CH₂O,CO₂和CH₃OH这些热反应产物. 紫外激光照射实验结果表明光照可以促进CH₃OH/CH₃O^·解离形成CH₂O,在程序升温或光照的过程中它又可以转变为HCOO^-. CH₂OH_Zn与OH_ad反应在Zn位点上形成H₂O分子. 升温或光照都能促进CH₃O^·转变为CH₃^·. 该研究对CH₃OH在ZnO(0001)表面的光催化反应机理提供了一个新的见解.     

Nb3Sn正常-超导转变时的比热反常

在16.0°K—20.3°K之间测量了Nb₃Sn样品的热容量。Nb₃Sn在临界温度附近的比热跳跃值ΔC=2.21(±5％)焦耳/克分子·度。样品的临界温度T_c=17.88°K,转变宽度ΔT_c≈0.2°K。ΔC值利用热力学关系式确定了Nb₃Sn在0°K时的热力学临界场H₀=5300奥斯特。利用本文的结果和文献上关于热膨胀系数的跳跃值Δα及?T/?P值验证了热力学关系式。扼要地描述了比热测量装置.     

Photoluminescence of a-Si:H films grown by plasma-enhanced chemical vapor deposition and doped with erbium from the metallorganic compound Er(HFA)3·DME

Using standard low-temperature (<300 °C) plasma-enhanced chemical vapor deposition (PE CVD) technology, films of a Si(Er): H were obtained that emitted light in the neighborhood of 1.54 μm at room temperature. The Er source was the specially synthesized fluorine-containing metallorganic complex Er(HFA)₃·DME where HFA=CF₃C(O)CHC(O)CF₃ and DME=CH₃OCH₂CH₂OCH₃, which possesses a low transition temperature to the gas phase (of order 100 °C) at working pressures (0.1–0.5 Torr) for the PE CVD method. Distinctive features of the photoluminescence spectrum of a-Si(Er):H were investigated in the range 0.5–1.7 μm for T=77 and 300 K. The presence of photoconductivity in the synthesized films is evidence of their satisfactory electronic quality. Fiz. Tverd. Tela (St. Petersburg) 40, 1433–1436 (August 1998)     

水/空气界面纳米颗粒单层膜流变特性的 锥体压入法研究

本文提出了利用锥体压入法研究水/空气界面上SiO₂纳米颗粒单层膜流变特性的新方法. 通过锥体的压入和上升使单层膜产生应变, 实时测定锥体压入-上升循环过程中表面压的变化. 实验表明, 表面压的尖锐变化是由单层膜受到的拉伸应变导致的. 表面压变化的幅度d∏ 和弛豫时间τ 显著依赖于颗粒在界面的吸附能, 因而随颗粒润湿性而发生明显变化. d∏ 和τ 分别与单层膜的弹性和黏性相关. 这些结果表明, 该方法有可能为深入研究纳米颗粒单层膜的流变性质提供新的途径.     

硫酸羟胺及亚硝酸钠对高碳钢表面锌系磷化涂层的组织和摩擦性能的影响

研究了在锌系磷化液中添加环保型促进剂-硫酸羟胺与常规促进剂-亚硝酸钠以便在高碳钢表面形成锌系磷化涂层．用X射线衍射分析了磷化涂层的相结构的变化,结果发现,形成的磷化膜主要由Zn₃Fe(PO₄)₂·4H₂O(H膜)和Zn₂Fe(PO₄)₂·4H₂O(P膜)组 成．运用扫描电镜分析了磷化涂层的显微组织与磷化时间之间的变化规律．四球摩擦实验结果表明,与亚硝酸钠相比,在锌系磷化液中添加硫酸羟胺能有效降低润滑后的磷化涂层的摩擦系数．     

深紫外和频晶体CLBO产生193 nm激光的频率变换

 简述了深紫外和频晶体CLBO的光学特性。根据相位匹配角公式、非线性有效系数公式、走离角公式和允许角公式，详细计算了CLBO晶体和频产生193 nm激光时的相位匹配角、非线性有效系数、和频时谐波走离角、允许角的具体数值。根据这些数值，并考虑产业化的要求，对目前几种和频方式进行了比较，最终选定波长为λ₁=2 100 nm的o光和波长为λ₂=213 nm的e光作为基频光进行和频的匹配方式。此方式相位匹配角为51.6°，具有大的非线性有效系数0.97，小的走离角3.7°，大的允许角1.9×10^-6 rad·mm，是非常理想的产生193 nm激光的匹配方式。     

表面热透镜技术测量3.8μm和2.8μm激光薄膜的微弱吸收

 采用表面热透镜技术，对3.8μm和2.8μm激光辐照下镀制在Si基底上的单层ZnS，YbF₃和YBC薄膜及不同膜系的YbF₃/ ZnS多层分光膜和多层高反膜，以及镀制在CaF₂基底上的增透膜进行了吸收测量，并对3.8μm和2.8μm 激光的测量结果进行了比较分析。实验结果表明，2.8μm波长下的吸收比3.8μm的大得多，两者之间约相差一个量级，测得的多层高反膜YbF₃/ZnS薄膜在的3.8μm处的最低吸收为4.57×10^－4，测量系统的灵敏度约为10^-5。     

二甲基亚砜溶剂中All-trans-astaxanthin的拉曼和红外光谱

The Raman and infrared spectra of all-trans-astaxanthin (AXT) in dimethyl sulfoxide (DMSO) solvent were investigated experimentally and theoretically. Density functional cal-culations of the Raman spectra predict the splitting of the υ₁ band into υ_1-1 and υ_1-2 compo-nents. The absence of splitting in Raman experimental spectra is ascribed to the competition between the two symmetric C=C stretching vibrations of the backbone chain. The υ₁ band is very sensitive to the excitation wavelength: resonance excitation stimulates the higher-frequency υ_1-2 mode, and off-resonance excitation corresponds to the lower-frequency υ_1-1 mode. Analyses of the intramolecular hydrogen bonding between C=O and O-H in the AXT/DMSO system reveal that the C4=O1...H1-O3 and C4''=O2...H2-O4 bonds are strengthened and weakened, respectively, in the electronically excited state compared with those in the ground state. This result reveals significant variations of the AXT molecular structure in different electronic states.     

Surface energy modification by electron beam

We observe a pronounced variation of wettability properties in solid state materials induced by a low-energy electron beam. The phenomenon occurs in several stages characterized by various mechanisms. We show that for low electron doses the irradiation leads to decrease in the wetting of a dielectric surface due to induced surface electric potential. The higher electron charge leads to formation of a chemical monolayer on material’s surface. It has been found that the electron irradiation strongly modifies the surface free energy of SiO₂ by decreasing its total surface free energy value, almost twice. However, electron-induced variations of dispersive and polar components of the surface free energy are quite different and depend of incident electron charge.     

Surface and transport properties of Au-In liquid alloys

Thermodynamic quantities on Au-In liquid alloys have been used as the input data for the interaction parameter calculations in the framework of the complex formation model (CFM). Once the interaction energies are computed the surface (surface tension and surface composition) and transport properties (chemical diffusion and viscosity) as well as the microscopic functions (concentration fluctuations in the long-wavelength limit and chemical short-range order parameter) have been calculated. The concentration and temperature dependent surface tension values have been compared with our new set of experimental data, obtained by the large drop method in the temperature range of T = 1273-1493 K. The anomalous change of surface tension for some alloy compositions may be attributed to a retention of order in the Au-In melts which is similar to the atomic arrangement in solid Au-In.     

纳米粒子形貌与表面等离子体激元关系

通过调控纳米粒子表面形貌,研究了纳米粒子形貌与表面等离子体激元之间的关系.采用水相化学合成法制备出粗糙表面“花朵”形银纳米粒子.通过自组装形成单层阵列,并进一步组装成复合结构超材料.测试了其光学行为,并将实验结果与树枝形纳米粒子、光滑表面纳米粒子进行对比分析.结果表明:光滑表面纳米粒子不能出现超材料效应,当粗糙程度增加,纳米粒子呈类“花朵”形时,样品出现透射峰和平板聚焦行为,但强度不高|当粗糙程度继续增加,纳米粒子呈树枝状时,出现了较强的透射峰与平板聚焦行为.研究证实通过改变纳米粒子表面形貌,可以调控表面等离子体激元与入射光的相互作用,从而实现对光传播的操控.     

Surface plasmon polariton scattering by small ellipsoid particles

Scattering of surface plasmon polaritons (SPP’s) by small ellipsoid particles placed near a dielectric–metal interface is theoretically considered. Using the Green’s function formalism and the dipole approximation, we consider the differential and total scattering cross-sections associated with the SPP-to-SPP scattering as well as with the SPP scattering into waves propagating away from the interface, analyzing the influence of system parameters. As an example, scattering cross-sections of differently shaped gold spheroid particles placed near an air–gold interface are evaluated at the light wavelength of 800 nm. It is shown that the differential and total cross-sections depend strongly upon the particle-to-surface distance, the ratio between the major and minor axes and their orientation with respect to both the interface and the direction of SPP incidence. Implications of the obtained results to the design of SPP micro-optical components are also discussed.     

Surface plasmon resonance polarizator for biosensing and imaging

A novel polarization-sensitive surface plasmon resonance (SPR) biosensing/imaging scheme is proposed. The scheme uses a periodical spatial phase modulation of the pumping beam of a mixed polarization in the Kretschmann–Raether geometry and takes advantage of SPR-based polarizing effect to drastically absorb p-polarized component changing the resulting polarization state of the beam. The scheme then uses Fourier Transformation to efficiently treat and filter spatially-modulated polarization-sensitive signals and thus to extract and process selected SPR-based response. This approach offers a much higher accuracy of measurements in SPR-based multi-sensing and remote sensing.     

Investigation of surface properties of liquid transition metals: Surface tension and surface entropy

In the present study, surface properties namely surface tension and surface entropy of liquid transition metals have been reported. The surface entropy of liquid Fe, Co and Ni metals has been investigated using the expression derived by Gosh et al. [R.C. Gosh, A.Z. Ziauddin Ahmed, G.M. Bhuiyan, Eur. Phys. J. B 56 (2007) 177]. To describe interionic interaction the pseudopotential approach has been used and radial distribution functions have been determined from the solution of Ornstein-Zernike integral equation. The calculated values of surface tension and surface entropy agree well with experiment. The present study shows that the expression derived by Gosh et al. leads to a good estimation for the surface entropy.     

Surface modification of silica-coated zirconia by chemical treatments

Zirconia surface modification by various chemical treatments after silica coating by sandblasting was investigated in this study. The surface of silica-coated dental zirconia was hydroxylated by treatment with different acids at room temperature for 4 h, rinsed with deionized water and air-dried. The modified surfaces were characterized by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Shifts in binding energies for Zr 3d_5/2 and Si 2p peaks were observed after treatment with acids, thereby showing a change in the chemical states of zirconium and silicon on the surface layer of silica-coated zirconia. The XPS analysis revealed that the silica-coated zirconia (SiO₂-ZrO₂) surfaces had changed to hydrous silica-coated zirconia (SiO₂-ZrO₂·nH₂O). One-way ANOVA analysis revealed there was significant difference in both surface roughness parameters of silica-coated zirconia after chemical treatments and the surface topography varied depending on the acid treatment.     

Surface structure and energy of B2 type intermetallic compound NiAl

The surface structure and energies for 22 surfaces of NiAl, an ordered intermetallic compound of B2 structure, have been studied by using embedded atom method. The results show that, for alternating Ni and Al surfaces with odd numbers of the sum of their three Miller indices, the energy difference between the Ni terminated surface and Al terminated surface increase linearly with increasing the interlayer distance. So from surface energy minimization, the Al terminated surface is favorable for each alternating Ni and Al surface. This is in agreement with experimental results. However, the energy of the (1 1 0) surface belonged to the other kind of the surface consisted of stoichiometric atomic layers and with even numbers of the sum of their three Miller indices, is the lowest in all two kinds of the surfaces. Therefore the (1 1 0) texture of NiAl appears mostly in the experiments.     

Surface science of diamond: Familiar and amazing

The crystal structure of diamond is identical with that of its more common semiconductor relatives silicon and germanium. Consequently, a number of surface properties in terms of reconstructions, surface states and surface band diagrams are similar as in the case of Si or Ge. But diamond also exhibits a number of unusual and potentially very useful surface properties. Particularly when the surface dangling bonds are saturated by monovalent hydrogen atoms (donor-like), surface states are removed from the gap, the electron affinity changes sign and becomes negative, and the material becomes susceptible to an unusual type of transfer doping where holes are injected by acceptors located at the surface instead of inside the host lattice. These surface acceptors can in the simplest case be adsorbed molecules conveniently chosen by their electron affinity, but they can also be solvated ions within atmospheric water layers or electrolytes in contact with the hydrogenated diamond surface. In this article the surface properties of diamond will be reviewed with special emphasis on this new kind of doping mechanism.     

Surface self-diffusion of quench condensed hydrogen films

The annealing behaviour of quench condensed H₂-, HD- and D₂-films has been investigated using acoustic surface waves. Upon annealing at temperatures far below the triple point we observe drastic changes of sound velocity and attenuation which can be attributed to a considerable rearrangement of the film structure via surface diffusion. These findings are in good agreement with recent experiments using surface plasmons. From the temperature dependence of the speed of the structural changes we deduce the activation energies for surface self-diffusion as 23 K, 35 K, and 47 K for H₂, HD, and D₂, respectively.