光电变色器件用纳米晶氧化钛薄膜的微结构与特性

纳米晶TiO2薄膜在光电变色器件中具有很重要的作用。它的微结构直接影响染料的吸附、光的散射以及电荷输运的特性。因此，探索TiO2薄膜的微结构(如粒径、表面形貌和厚度等)及光电性能是非常有意义的。采用电子束蒸发工艺制备了光电变色器件用纳晶TiO2薄膜，利用原子力显微镜、X射线衍射、俄歇电子能谱等手段对纳米晶TiO2薄膜的表面形貌、结晶状态及组分进行了分析。从理论上研究和讨论了纳米晶TiO2薄膜晶粒尺寸对光电性能的影响，并用量子限制效应解释了吸收光谱峰值波长随粒径减小而发生蓝移的现象。     

Theoretical study on line source laser-induced surface acoustic waves in two-layer structure in ablative regime

The generation of ultrasound in film–substrate system by a laser line source is studied in the case of ablation mechanism, which can be realized by adding a liquid layer at the excitation point. The time domain displacement can be yielded by the numerical jointed inversed Laplace–Fourier transformation technique. The typical surface acoustic waves (SAW) of two layer structures, slow film on fast substrate and fast film on slow substrate, are obtained and the effect of the propagation distance and the thickness of the film on the SAW are given.     

The structure of multi-electrode-pair pulse laser and discharge pulse time selection

Applying multi-electrode-pair pulse TEA CO₂ laser to one optical resonance cavity will have several advantages over traditional method, including higher gain, shorter pulse discharge time interval, and in particular, continuous adjustable time interval of multi-pulse laser output can be achieved without high vacuum condition. To improve laser's working stabilization, we proposed new approaches to optimize laser structure design and discharge pulse time interval selection.     

Electronic structures and ferroelectric properties of ABi2Ta2O9 (A=Ca, Sr, and Ba)

The electronic structures of ABi₂Ta₂O₉ (A=Ca, Sr, and Ba) were calculated by using first-principles under optimized structure. As the size of A-site cation decreases from that of Ba²⁺ to Ca²⁺, the band-gap between O 2p and Ta 5d increases from 2.0 to 2.9 eV, which responses to the stronger orbital hybridizations between Ta 5d and O 2p orbits favoring improvement of the ferroelectric property, decrease in leakage current, and increase in both spontaneous polarization and Curie temperature by the structural distortion. In contrast to CaBi₂Ta₂O₉ and SrBi₂Ta₂O₉, the hybridization between Ba 5p orbits and O 2p orbits in BaBi₂Ta₂O₉ has better structural stability.     

Vanishing Shear Viscosity Limit in the Magnetohydrodynamic Equations

We study an initial boundary value problem for the equations of plane magnetohydrodynamic compressible flows, and prove that as the shear viscosity goes to zero, global weak solutions converge to a solution of the original equations with zero shear viscosity. As a by-product, this paper improves the related results obtained by Frid and Shelukhin for the case when the magnetic effect is neglected. Supported by NSFC (Grant No. 10301014, 10225105) and the National Basic Research Program (Grant No. 2005CB321700) of China.     

非本征型法布里-珀罗干涉仪光纤布拉格光栅应变温度传感器及其应用

介绍了光纤布拉格光栅非本征型法布里珀罗干涉仪集成复用传感器的结构、应变和温度同时监测的原理 ;观察到光纤布拉格光栅反射谱和非本征型法布里珀罗干涉仪干涉谱间的串扰 ,用 3dB带宽平均波长法减小了该串扰 ,提高了测量精度 ;将该传感器应用于三维编织复合材料的应变及温度同时监测。实验结果表明温度精度为± 1℃ ,应变精度为± 2 0 μ ,可满足实际应用的要求     

Spin-Dependent Transport and Densities of States in Non-collinear Magnetic Barriers

The spin-dependent transport properties in the non-collinear pattern of series of δ-magnetic barriers are studied by using scattering theory and Green‘s function methods. The Green‘s function is obtained by using distorted wave approach and the scattering matrix is related by Fisher-Lee relationship. In addition to reproducing the results of Papp‘s and Xu‘s in parallel and antiparallel configurations, we also obtain further results, where arbitrary orientations of the magnetic barriers and arbitrary number of barriers are included. The main finding of our results is that the signs of polarizations can be switched around some “geometric unpolarized windows“. The well-known antiparallel configuration has no such characteristics. Furthermore, we discuss spin-related partial densities of states in both polarized and unpolarized structures.     

New BCN Fibres for Strong Ultraviolet and Visible Light Luminescence

Novel B3CN3 fibres with a special structure have been synthesized by a pyrolysis process. High-resolution TEM analysis shows that the as-prepared B3CN3 fibres can be described as a nanofibre-interweaved network. Strong photoluminescence at 370 nm and 700 nm from the as-prepared B3 CN3 fibres are observed at room temperature, which suggests that B3 CN3 is a promising ultraviolet- and visible-light-emitting material.     

对称正则长波方程的一个守恒差分格式

本文考虑了具有齐次边界条件的对称正则长波方程的有限差分法．构造了一个两层守恒的有限差分格式,利用离散泛函分析方法分析了格式的收敛性和稳定性,从理论上得到了收敛阶为O(h~2 τ)．数值试验表明,我们的方法是可信的．     

Interference Diagnosis of the Initial Stage of Laser-Produced-Plasma in Air

By using a Q-switched YAG Laser and a optical path delay set-up, we study the process in whith a laser induces breakdown to produce plasma in air, and obtain time-resolved Mach-Zehnder interferograms and optical shadowgrams of the initial stage of the plasma and the expansion wave produced in the process for the first time