Ab-initio Hartree-Fock self-consistent-field calculations—An indigenous development of computer programs

A set of indigenously developed computer programs for ab-initio Hartree-Fock calculations on both closed- and open-shell molecules have been described. These programs have been written for calculations using GTO basis sets. Integral formulae have been taken from Taketaet al [8]. Structures and functions of the programs have been discussed. These programs have been extensively tested. Molecular integrals over GTO basis sets have been chosen for tests and as numerical examples in this paper. Results of calculations using very accurate minimal bases have been given for methane. Time taken for these computations in a CDC Cyber 180/840 machine has been indicated. Trends in the calculations have also been illustrated by employing 4-gaussian expansions for the STO’s and by varying the basis size for LiH and BH⁺. An erratum to this article is available at .     

Spectroscopic properties of Yb3+-doped Y3Al5O12 nano-ceramics obtained under different sintering pressures

Yb³⁺:YAG nano-ceramics have been obtained by a low temperature/high pressure sintering process. Structural properties have been studied by X-ray diffraction (XRD). Grain sizes and R.M.S micro-strains have been calculated based on the XRD patterns by Rietveld analysis method. Emission spectra and decay curves have been recorded and analyzed. It has been observed that the decay time decreases with the increase of sintering pressure. Presence of Yb³⁺–Yb³⁺ pairs have been detected by cooperative emission spectroscopy.     

Modifying a graphene layer by a thymine or a uracil nucleobase: DFT studies

The hybridizations of a graphene layer by a thymine and a uracil nucleobase have been investigated by performing density functional theory (DFT) calculations. The isolated and hybrid structures have been firstly stabilized to reach the minimum energy and the electronic properties have been subsequently evaluated for the optimized structures. The structural and atomic scale parameters indicated that the tip of graphene is important in determining the properties of new hybrids. Moreover, different effects of thymine and uracil nucleobases have been identified in the hybrid structures. Quadrupole coupling constants have been evaluated to characterize the atomic scale properties, in which the most notable effects of hybridizations have been observed for the atoms close to the linking regions whereas negligible effects have been seen for other atoms.     

电子束在VO2薄膜中引起的价态、相结构和光学性能的改变

 利用能量为1.7MeV, 注量分别为1.25×10¹³/cm², 1.25×10¹⁴/cm², 1.25×10¹⁵/cm²的电子束辐照VO₂薄膜,采用XPS, XRD等测试手段对电子辐照前后的样品进行分析,并研究了电子辐照对样品相变过程中光透射特性的影响。结果表明电子辐照引起VO₂薄膜中V离子出现价态变化现象,并使薄膜的X射线衍射峰发生变化。电子辐照在样品中产生的这些变化显著改变了VO₂薄膜的热致相变光学特性。     

Raman Scattering by Crystals of Rare-Earth Hexaborides with Different Isotopes of Boron

Monocrystals of lanthanum hexaboride LaB₆ containing both natural boron and its isotopes ¹⁰B and ¹¹B have been produced using the solution-melt method. Polyelement hexaboride rare-earths have been grown and the corresponding ceramics have been synthesized for the first time. All these crystals have been studied by means of various techniques, generally using Raman scattering. The Raman spectra attributed to various spectral lines corresponding to nonanalyzable representations have been obtained and interpreted. Frequencies and half-widths of spectral lines have been obtained, the removal of degeneracy and the development of respective splitting of degenerate oscillations induced by defects, mainly by boron isotope inclusions, have been identified. The influence of defects on the Raman spectra has been determined.     

插入生长AlGaAs薄膜对InAs量子点探测器性能的影响

利用分子束外延生长获得的两个InAs量子点样品制备了n型的量子点红外探测器.对于其中一个器件，在InAs量子点有源区的底部和顶部分别插入生长了AlGaAs势垒层.利用透射电阻显微技术研究了两个样品的结构特性；利用光致发光光谱和光电流谱研究了两个器件的光电性质.实验结果表明，AlGaAs层的插入对器件的探测性质有显著的影响.利用有三维效质量近似模型的计算结果，指认了带内光电流谱中峰结构的起源.     

插入生长AlGaAs薄膜对InAs量子点探测器性能的影响

利用分子束外延生长获得的两个InAs量子点样品制备了n型的量子点红外探测器.对于其中一个器件,在InAs量子点有源区的底部和顶部分别插入生长了AlGaAs势垒层.利用透射电阻显微技术研究了两个样品的结构特性;利用光致发光光谱和光电流谱研究了两个器件的光电性质.实验结果表明,AlGaAs层的插入对器件的探测性质有显著的影响.利用有三维效质量近似模型的计算结果,指认了带内光电流谱中峰结构的起源. 关键词： InAs 量子点 AlGaAs薄膜 光致发光光谱 有效质量近似模型     

Synthesis,growth and characterization of 4-dimethylaminobenzaldehyde-4-nitrophenylhydrazone single crystals

4-Dimethylaminobenzaldehyde-4-nitrophenylhydrazone (DANPH) single crystals exhibit polymorphism such as DANPH-G form (greenish red) and DANPH-R form (red). The different polymorphic phases of the grown crystals have been identified by X-ray diffraction studies. The functional groups of the crystals have been identified by FT-IR study. Crystallographically independent environment of polymorphs has been confirmed by NMR study. The thermal properties such as melting and decomposition temperatures of the compound have been analyzed. Optical constants of DANPH polymorph crystals have been calculated.     

Some physical properties of In doped copper oxide films produced by ultrasonic spray pyrolysis

In this work, we have reported the effect of In doping on structural, optical and surface properties of copper oxide films obtained by a low-cost ultrasonic spray pyrolysis technique. Thicknesses, refractive indices and extinction coefficients of the films have been determined by Spectroscopic ellipsometry technique using Cauchy-Urbach model for fitting. A very good agreement was found between experimental and theoretical parameters with low MSE values. Transmission and reflectance spectra have been taken by UV Spectrophotometer, and band gap values have been determined by optical method. Structural properties of the films were investigated with X-ray diffraction patterns. In doping caused the films to growth through some certain directions. Atomic force microscope images have been taken to see the effect of In doping on surface topography and roughness of copper oxide films. Surface properties of undoped films have been improved by In doping. Lowest roughness values have been obtained for In doping at 1%. As a result, we have concluded that properties of copper oxide films which are commonly used in solar cells may have improved by In doping (especially In doped at 1%).     

The characteristic equation and solution of circular-groove guide

The characteristic equations of circular-groove guide have been given under first-order and second-order approximation. The cutoff wavelength and guide wavelength have been calculated. The theoretical results have been verified by experimental measurements.Supported by the Natural Science Fundation of P. R. China     

Silicon rich silicon oxide films deposited by radio frequency plasma enhanced chemical vapor deposition method: Optical and structural properties

Silicon rich silicon oxide films have been deposited by plasma enhanced chemical vapour deposition using a gas mixture of silane, carbon-di-oxide and hydrogen. Silicon nanocrystals formations in the as deposited silicon rich silicon oxide films have been detected by high resolution transmission electron microscopy, scanning electron microscopy, Raman scattering and X-ray diffraction studies. Structural changes under different deposition condition have been studied by Fourier transform infrared spectroscopy. The oxygen and hydrogen bonding configurations have been obtained from Fourier transform infrared spectroscopy. Room temperature photoluminescence spectra have been observed for the as deposited films. The structural properties together with photoluminescence spectra allowed us to gain insight about the Si nanocrystal formation.     

Acoustic analog of monolayer graphene and edge states

Acoustic analog of monolayer graphene has been designed by using silicone rubber spheres of honeycomb lattices embedded in water. The dispersion of the structure has been studied theoretically using the rigorous multiple-scattering method. The energy spectra with the Dirac point have been verified and zigzag edge states have been found in ribbons of the structure, which are analogous to the electronic ones in graphene nanoribbons. The guided modes along the zigzag edge excited by a point source have been numerically demonstrated. The open cavity and “Z” type edge waveguide with 60° corners have also been realized by using such edge states.     

Investigation of the ETA-BETA II plasma edge by surface analysis of collector probes

To investigate the ion flux escaping from the plasma and the impurity flux released by the wall, collector probes made of graphite, silicon and titanium have been exposed to the deuterium plasma confined in the toroidal device ETA BETA II. The damages on the collector surfaces have been surveyed by a scanning electron microscopy (SEM) apparatus. The deuterium and impurity retention have been measured by elastic recoil detection (ERD) and Rutherford backscattering spectroscopy (RBS) techniques respectively. The implantation build-up has been investigated as a function of the exposure time. The deuterium dose in graphite saturates after a few discharges, whereas the metal impurities exhibit a linear increase in time. The deuterium flux and its radial dependence, inferred from the implanted concentrations, have been compared with those measured by Langmuir probes. Metal impurities have been identified and their relative abundances have been compared with the material wall composition. The impurity flux is found consistent with the global content in the plasma derived by spectroscopic measurements. The deuterium dose measured in different samples has been related to the backscattering coefficient of the materials. Finally, to investigate the damage on sample probes facing the plasma particle flow, erosion probes made of vitreous graphite with silver implanted at a fixed depth have been exposed to the plasma and the thickness change after exposure recovered.     

Theoretical permittivity spectra of isoelectronic Ge, GaAs, ZnSe, and CuBr crystals

Comprehensive theoretical investigations of the electronic structure of isoelectronic Ge, GaAs, ZnSe, and CuBr crystals have been carried out. The band structure has been calculated by the LAPW method. The total and partial densities of states have been determined and the permittivity spectra have been calculated by the tetrahedron method. The nature of maxima of the ?₂ band spectra and their dependence on the chemical bond type have been determined.     

Temperature tunable optical gratings in nematic elastomer

We have investigated the behaviour of temperature dependent periodic-index gratings fabricated in a nematic elastomer. The gratings have been obtained by photopolymerisation under a microscopy apparatus. Contraction properties, as well as diffraction properties, have been studied as a function of temperature. Unidirectional contraction has been demonstrated by means of circular figure deformation and the polarisation dependency of the diffraction by the gratings has been determined.     

Identification des propriétés thermiques de composites fibres de verre/résines thermodurcissables: Application à l'optimisation des procédés de moulage

Identification of glass fiber/thermosetting resins composites thermal properties. Application to the optimization of molding processes. A procedure has been developed to optimize molding processes of thermosetting composite materials. Three stages have been distinguished. In the first one, some thermal and kinetic properties have been measured by differential scanning calorimetry. Thermal conductivities have been identified afterwards in thick instrumented pieces, placed in a thermally regulated press. High dependences of thermal conductivities on temperature and transformation degree have been shown. Secondly, coupled heat transfers have been numerically simulated and results have been satisfactorily compared with experimental thermograms. Finally, optimization technics based on effective inverse methods have been used.These points have been illustrated with two examples : glass fiber/epoxy resin and glass fiber/polyester. Sufficient mechanical characteristics of the first one, which is cured in oven, and good surface aspect of the second, that is made by injection in heated and closed molds, had to be obtained. The results let foresee real improvement of the corresponding molding processes.     

Studies of phase transitions and ferroelastic domain walls in Pb5Al3F19 crystals by optical measurements

Three phase transitions between 100 and 400 K were previously shown by X-ray diffraction measurements. Such results have been confirmed by optical measurements on crystals. The thermal dependence of the birefringence has been determined. A new phase transformation has been shown at around 590 K not only by optical study but also by dielectric measurements. Ferroelastic domain-walls have been visualized. The sequence transition has been discussed taking into account the various space groups.     

Electron spin relaxation times and internal motions of radicals in the solid state investigated by ENDOR and pulsed EPR

The angular dependent ENDOR spectra of the radical formed by ψ-irradiated single crystal of 4-methyl-2,6-di-t-butylphenol have been studied and the full hyperfine tensors of all the t-butyl and the ring protons have been obtained atT=190 K. We found six different tensors for the t-butyl protons. This result shows that the t-butyl groups are slowly rotating on the ENDOR time scale, whereas each methyl group rotates fastly. The dynamical parameters of the motions have been determined by pulsed EPR experiments. The longitudinal relaxation and the phase memory times have been measured in the temperature range 130–290 K. Three different kinds of motions have been detected and the resulting values of the dynamical parameters have been compared with those obtained for the undamaged molecule by previous NMR studies.     

Synthesis,experimental and theoretical analysis,and antiproliferative activity of 2-(4-methoxyphenylamino)-2-oxoethyl methacrylate

In this study 2-(4-methoxyphenylamino)-2-oxoethyl methacrylate (MPAEMA) has been synthesized and characterized experimentally (FTIR, NMR). Theoretically, physical, electronic and vibrational properties of MPAEMA molecule have been investigated using density functional theory (DFT) calculations at B3LYP/6-311++G(d,p) basis set. Bond distance, FTIR spectrum, NMR spectra and vibrational frequencies have been carried out. The calculated FTIR and NMR spectra of the headline molecule from the DFT have been compared with the measured ones, and good results have been obtained. UV spectrum characteristics and the electronic properties, like frontier orbitals, and band gap energy of MPAEMA have also been recorded by time-dependent (TD-DFT) method based on optimized structure with different solvent. The experimental results have been compared with theoretical values. Both experimental and theoretical methods have shown that the compound has successfully been synthesized. Cytotoxicity of MPAEMA has been investigated by XTT cell proliferation assay. IC50 values of MPAEMA have been identified as 1.8 mM on HeLa cell line.     

ICP－AES测定蔬菜中18种矿物元素的研究

本文探讨了ＩＣＰ－ＡＥＳ测定蔬菜中１８种矿物元素的方法，选择了合理测试条件。用国家计量局批准的ＧＢＷ０８５０４甘蓝标准物质核对了其中十种元素，得到满意结果。并用该法进行了样品分析，方法简便、快速。