分散有ZnS:Mn2+纳米超微粒的有机薄膜的制备和光学性质

近年来,半导体超微粒的合成及光物理性质研究已成为活跃的领域.由于量子尺寸效应引起的量子点能级结构的变化及其光学性质已经作了大量研究[1-4].1993年,Bhar-gava首次报导了化学反应合成的ZnS Mn超微粒的光学性质[5],掺杂半导体纳米材料的出现,为纳米科学的研究开辟了新的领域.     

二维频域波束形成方法

一般来讲，无论雷达或声纳从基阵接收的信号均是多维信号，本文将在二维频率域对窄带传输信号进行分析与描述，研究线列阵的波束形成问题，根据分析结果并考察了几种特例。     

Direct visual evidence for chemical mechanisms of SERRS via charge transfer in Au20–pyrazine–Au20 junction

The essence of the chemical mechanism for surface‐enhanced resonance Raman scattering (SERRS) is the charge transfer (CT) between the metal and the molecule at the resonant electronic transition, which results in the mode‐selective enhancement in the SERRS spectrum. The site‐orientated CT can directly interpret the mode‐selective chemical enhancement in SERRS. However, it is a great challenge to intutively visualize the orientation and site of the CT. In this paper, for the pyrazine–Au₂ complex, a three‐dimensional (3D) cubic representation is built to provide direct visual evidence for chemical mechanisms of SERRS via CT from the Au₂ cluster to pyrazine at the resonant electronic transition. The relationship between the mode‐selective enhancements in SERRS and the site‐orientated CT was clearly revealed. The intracluster excitation (analog of plasmon excitation in large naonoparticles) was also visualized by the 3D cubic presentation, which provided the direct evidence of local electromagnetic field enhancement of SERRS. To study the quantum size effect and the coupling effect of the nanoparticles, the photoexcitation mechanisms of the Au₂₀–pyrazine complex and the Au₂₀–pyrazine–Au₂₀ junction were also investigated. The tunneling charge transfer from one Au₂₀ cluster to another Au₂₀ cluster outside the pyrazine in Au₂₀–pyrazine–Au₂₀ junction was also revealed visually. The calculated normalized extinction spectra of Au nanoparticles using the generalized Mie theory reveal that the resonance peak is red‐shifted due to the coupling between particles. Copyright © 2009 John Wiley & Sons, Ltd.     

关于刚体转动惯量测定的计时方法研究

本文给出了在刚体转动惯量的测定中测定时间的计时装置，减小了计量时间所带来的误差。     

外加电场对光折变高阶响应影响的微扰分析

应用微扰展开法了“跳跃模型”给出了空间电荷场前三阶分量随时间，外加电场等变化的解析表达式，同时讨论了外加电场对各阶空间电荷场建立的影响，当扩散与外加电场可比拟时，外加电场对空间电荷场的影响不大，随着空间电荷场阶数的提高，其达到最大饱和值所需的外加电磁越小，在外加电场作用下，空间电荷场各阶分量随时间呈振荡衰减，直到达到饱和，外加是场越大，振荡越强烈，周期越短，在考虑高阶分量的贡献后，空间电荷场的振荡     

电磁内爆的准一维数值模拟

 提出一个用于电磁内爆过程数值模拟的准一维模型，对1 MJ电容器组电磁内爆优化方案进行了计算，并将计算结果与零维模型和一维模型的结果进行了比较。     

钝感炸药圆筒试验与爆轰产物JWL状态方程研究

 对以TATB为主的钝感炸药JB-9014进行了25 mm和50 mm两种装药直径的圆筒试验，测试了TU1圆筒在爆轰产物驱动下的膨胀过程R(t)关系。对圆筒试验进行了综合分析和二维数值模拟计算，综合评估了JB-9014的作功能力和圆筒试验的相似性。通过二维流体动力学数值模拟，确定得到了JB-9014炸药爆轰产物JWL状态方程参数。经对JB-9014二维平面滑移爆轰驱动试验的数值模拟检验，证明确定的JWL状态方程参数是可靠的，具有较高的精度和普适性。     

铝靶激光热应力的实验研究

 用高温应变计和热偶计等诊断技术，研究连续波氧碘化学激光（CW/COIL）与铝合金板作用产生的激光热应力。当照射靶面激光强度约1 000 W/cm²时，激光热应力随靶厚的增加而快速减小。当激光辐照靶材厚度h＝1.00 mm、激光强度I＝640~980 W/cm²时，激光热应力随辐照靶面激光强度的增加而增大。两者的激光热应力－时间曲线随靶厚的减薄或随辐照靶面激光强度的增加而变得越来越复杂。当靶厚h≤2.50 mm，辐照靶面激光强度I≥800 W/cm²时，激光热应力强度超过激光辐照区材料断裂强度，萌生许多孔洞裂纹，引起材料断裂破坏。     

Molecular Dynamics Investigation of Differences in Melting Behaviors of Cu57 and Cu58 Clusters

应用基于嵌入原子方法的分子动力学计算研究了Cu57和Cu58团簇在升温过程中变为熔体的结构演化过程．两个团簇在熔化时表现出不同的结构变化行为,进而影响到它们能量变化的差异．在升温时,团簇不同区域的原子局域结构变化由原子密度分布函数确定．模拟表明,即使对于这两个仅相差一个原子的小尺寸团簇,结构变化也敏感于团簇的尺寸．     

Preparation and microwave-absorbing properties of NiFe2O4-polystyrene composites

NiFe₂O₄ nanoparticles were synthesized by the polyacrylamide gel method with acrylamide as the monomer and N,N′-methylenediacrylamide as lattice agent. The average crystallite sizes of the nickel ferrites annealed at 500, 600 and 800 °C are about 10, 30 and 50 nm, respectively. Ferrite-polystyrene composites were made by hot pressing, and microwave-absorbing properties of the composites with different contents of 35, 45, 55 and 65 wt% ferrite were investigated by testing complex permeability and complex permittivity in the X-band (8.2-12.4 GHz) frequency range. All the parameters, ε′, ε″, μ′ and μ″, increase with increasing ferrite content. The reflection losses were calculated based on a model of a single-layered plane wave absorber backed by a perfect conductor. The composite with 65 wt% ferrite content shows a minimum reflection loss of −13 dB at 11.5 GHz with a −10 dB bandwidth over the extended frequency range of 10.3-13 GHz for an absorber thickness of 2 mm.