P_6团簇结构与稳定性的理论研究

采用量子化学HF,B3LYP和MP2方法,选用6-31G*,6-311G*,cc-pVDZ和cc-pVTZ基组,对P6团簇的8种异构体进行了优化,并对它们的几何构型、稳定性、电子结构和振动频率进行了讨论,比较P6团簇各种异构体的稳定性以及导电性.研究表明:根据异构体的相对能量,P6异构体最稳定的构型c具有C2v对称性,而最不稳定的构型h具有D3h对称性,不同方法和基组所得到的稳定性大小基本一致,并且得到结构g的导电性最好.     

Calculations of the vibrational frequency and isotopic shift of UF₆ and U₂ F₆

Molecular structure, vibrational frequency and infrared intensity of UF 6 are investigated by using the revised Perdew-Burke-Enzerhof function with the triple-zeta polarized basis set. The calculation results are in good agreement with the experimental values and indicate the existence of a stable U2F6 molecule with a multiple bonded U2 unit. The calculation results also predict that the D3d symmetry of U2F6 is more stable than D3h . The optimized geometries, vibrational frequencies, and infrared intensities are also reported for U2F6 molecules in D3d symmetry. In addition, the isotopic shift of vibrational frequencies of the two molecules under isotopic substitution of uranium atom are also investigated with the same method. The U2F6 molecule is predicted to be better than UF6 for laser uranic isotope separation.     

氘、氚代聚苯乙烯单体abinitio研究

用HF,MP2及BLYP从头算方法,在6—31G基组水平上,优化了聚苯乙烯单体基态的平衡几何构型.主要用BLYP6—31方法研究了氘、氚代聚苯乙烯单体(DPS,PST)的正则振动频率、红外光谱强度、C—D键键能,并对正则振动模式进行了简单分析,同时研究了DPS,PST单体中温度、压强与熵的关系.关键词：平衡几何构型正则振动频率红外光谱强度键能     

Kr对HF(X1Σ+)基频和泛频的影响

运用Monte-Carlo轨迹法研究了Kr(1Sg)+HF(X1Σ+;ν=1,2,3;J=4)→Kr(1Sg)+HF(X1Σ+,ν',J')的碰撞过程,从而分析Kr原子对HF基频和泛频的影响。研究表明：在初始相对平动能Et≤251.0kJ/mol时,Kr原子能够减少产生基频的粒子数反转,增加产生泛频特别是ν'=2能级的粒子数反转,并且,Kr原子有较强的弛豫高转动态（J'≥4）的能力,因此,Kr原子对HF泛频激光在提高光强和增强大气传输能力方面均有 较大的改善。     

Plasma-based sputtering of indium tin oxide for the application of photovoltaic cells

Transparent and conducting indium tin oxide (ITO) thin films were deposited on soda lime glass substrates by RF plasma magnetron sputtering at room temperature. The effect of thickness (100, 200 and 300?nm) on the physical (structural, optical, electrical) properties of ITO thin films was investigated systematically. It is observed that with an increase in thickness, the X-ray diffraction data indicate polycrystalline films with grain orientations predominantly along (222) and (400) directions; the average grain size increases from 10 to 30?nm; the optical band gap increases from 3.68 to 3.73?eV and the transmission decrease from 80% to 70% . Four-point probes show a low resistivity (2.4×10^?5?Ω?cm) values for film with a thickness 300?nm. Present work shows that the ITO is a promising transparent conductive oxide material for the solar cell application.     

The influence of the implantation temperature on the generation of dislocations in antimony-implanted and annealed silicon

We report the first observation of non-equilibrium redistribution effects during laser treatment of a binary system having equilibrium segregation coefficient, k₀, much greater than unity. Polycrystalline aluminium samples implanted with 30 keV Sb⁺ ions to a dose of 1.7 × 10¹⁷ ions/cm² were irradiated with single pulses (7 ns FWHM) from a Nd: glass laser operating in TEM₀₀ mode. The peak energy density (at the centre of the laser spot) varied from 2.0 to 5.7 J/cm². A detailed liquid phase diffusion analysis, explicitly incorporating rapid melt front motion and interfacial segregation, is performed to fit the Sb depth profiles measured with a nuclear microprobe. An effective distribution coefficient k = 1 (as compared to equilibrium value of k₀～7) is obtained in agreement with the theoretical limiting value for large melt front velocities.     

Humidity Sensing Using Gelatin and Cobalt Chloride Coating on Indium Tin Oxide-Coated Long-Period Grating

Abstract

In this article, humidity sensing using gelatin and cobalt chloride on indium tin oxide coated long-period gratings was proposed and demonstrated. First, a thin overlay of indium tin oxide was deposited on a long-period grating by using a simple dip coating methodology. Similarly, a combination of gelatin and cobalt chloride was deposited onto the indium tin oxide layer. A field emission scanning electron microscope provided detailed evidence of the attachment of amalgamation on long-period gratings. The designed sensor showed a significant shift in the resonance wavelength when the relative humidity varied from 40% to 95%, with a sensitivity of 0.12 nm/% relative humidity and an accuracy of 98.45%.     

OH− ions in Oxide Crystals

This article reviews the spectroscopic properties of hydrogen bound to a large variety of synthetic compounds like simple oxides, perovskites, the LiNbO₃ family, KTP, sillenites, eulytites, borates, garnets, spinels and some others. In almost all compounds the OH stretch mode is found in the range 3200-3700 cm^?1, with isotope replica of deuterium (2350-2750 cm^?1) and a few examples of tritium (2050-2250 cm^?1). The fundamental vibration, the isotope replica and the corresponding overtones are described with an anharmonic oscillator model. A nonlinear relation between the anharmonicity and the harmonic frequency is found and interpreted using recent second order perturbation calculations. An often pronounced temperature dependence of the stretch mode and phonon coupling is discussed. Data for the stretching vibration influenced by additional weak or strong doping are presented. Atomistic defect models are described and tested by means of light polarization, external perturbations like pressure and electric field, and Raman scattering analyzed with the behavior-type method. The last section briefly reviews applications profiting from doping with hydrogen and its easy detection by means of the OH stretch mode.     

Infrared spectra and structure of tetravalent uranium chloride nanoclusters in electron-donor solvents

We have studied the IR absorption spectra of tetravalent uranium chlorides in electron-donor solvents. We discuss the changes in these spectra on coordination of the solvent molecules to the tetravalent uranium. We consider the participation of water molecules in this process. On this basis, we draw the conclusion that clusters form with coordination number equal mainly to six. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 5, pp. 729–732, September–October, 2008.     

溶胶凝胶法制备以HfO2为绝缘层和ZITO为有源层的高迁移率薄膜晶体管

采用溶胶凝胶法制备了h-k氧化铪HfO₂薄膜, 经500℃退火后, 获得了高透过率、表面光滑、低漏电流和相对高介电常数的HfO₂薄膜. 并采用氧化铪作为绝缘层和锌铟锡氧化物作为有源层成功地制备了底栅顶接触结构薄膜晶体管器件. 获得的薄膜晶体管器件的饱和迁移率大于100 cm²·V^-1·s^-1, 阈值电压为-0.5 V, 开关比为5×10⁶, 亚阈值摆幅为105 mV/decade. 表明采用溶胶凝胶制备的薄膜晶体管具备高的迁移率, 其迁移率接近低温多晶硅薄膜晶体管的迁移率.     

氧化铟锡薄膜的二阶非线性光学特性研究

利用二次谐波产生技术研究了氧化铟薄膜的非线性光学特性.氧化甸锡薄膜中多晶晶粒的优先取向,使其产生了非常强的二次谐波信号,并且在一定的薄膜存度以上,随薄膜厚度的增加二次谐波信号显著增强.由于多晶晶粒的优先取向使得薄膜基板平面内存在着非常明显的非线性光学各向异性.     

Characterization of dip-coated ITO films derived from nanoparticles synthesized by␣low-pressure spray pyrolysis

In₂O₃:Sn (Indium Tin Oxide; ITO) films were prepared from a sol solution with highly crystalline ITO nanoparticles (less than 20 nm in size with 10 at.% Sn) which had been prepared by low-pressure spray pyrolysis (LPSP) in a single step. The ITO sol solution was prepared by dispersing LPSP-prepared ITO nanoparticles into ultra pure water. The nanoparticle ITO film was deposited on a glass substrate using a dip-coating method and then annealed in air at various temperatures. The optical transmittances of the ITO films were measured by UV–Vis spectrometry, and the films were found to have a high transparency to visible light (in the case of a film thickness of 250 nm annealed at 400°C, the transparency was in excess of 95% over the range λ=450–800 nm, with a maximum value near 100% at wavelengths above λ=700 nm). The optical transmittances of the films were influenced by the size of the ITO particle used, the film thickness and the annealing temperature. The ITO films showed a minimum resistivity of 9.5×10⁻² Ω cm, and their resistivity was affected by both the ITO particle size and the annealing temperature used.