1 kHz-0.1 TW高效率钛宝石激光放大器

介绍了一种高重复频率掺钛蓝宝石飞秒激光多通高效率放大系统.在抽运功率为23 W，入射功率为660 mW时，获得7.2 W的放大输出，放大效率达30%.经压缩器压缩后，获得单脉冲能量4.5 mJ,脉冲宽度为 38 fs，重复频率为1 kHz，峰值功率大于0.1 TW的超短超强激光脉冲. 关键词： 飞秒脉冲 高重复频率 啁啾脉冲放大     

高纯硅低能粒子辐照E′色心形成动力学研究

考虑固有点缺陷形成E′色心的情况，建立了E′色心形成的动力学模型，得到了高纯硅低能粒子辐照E′色心浓度与辐照剂量的关系式.结果表明，在低辐照剂量下，E′色心浓度随剂量的变化呈线性增长；随着辐照剂量的增加，E′色心浓度随剂量的变化呈饱和趋势.如果进一步考虑E′色心和其他物质反应形成新的稳定结构，E′色心浓度随剂量的变化呈双指数关系，E′色心浓度随剂量的变化不再趋于饱和状态，而是偏离饱和状态.理论结果和实验结果很好地符合，说明建立的模型是有效的.     

大型Schmidt望远镜光学系统调整方法

安装于紫金山天文台盱眙观测站用以观测近地天体的大型Schmidt望远镜,采用了平场Schmidt光学系统,改正镜通光口径为1m,球面反射镜口径为1.2m,焦距为1.8m,接收器用了4K×4K的高灵敏度CCD。本文叙述了该仪器光轴调整的方法及调整后观测获得的初步结果。叙述了望远镜光轴校正方法、校正结果、CCD靶面的调整及望远镜极轴高度、方位的调整及相应的照片。经实际观测的结果是:露光1s可拍到18等星;露光4s可拍到19.3等星;露光20s可拍摄到21.2等星。     

高压烧结法合成致密纳米BaTiO3陶瓷结构和铁电性能研究

 在6 GPa压力、1 000 ℃温度条件下制备了致密的纳米BaTiO₃陶瓷，合成样品的平均晶粒尺寸为50 nm，理论密度在97%以上。通过介电测量，观察到了样品宽化的相变峰，它与粗晶陶瓷的相变峰大不相同。由于90°电畴的减少和退极化场的存在，观察到了细长的电滞回线，它是样品铁电性存在的有力证据，表明钛酸钡陶瓷的临界尺寸在50 nm以下。     

第四讲 超强激光脉冲与等离子体相互作用中高能离子的产生

近几年来，由于高功率激光技术的不断发展，利用超强激光脉冲与等离子体相互作用产生高能离子束的研究得到了极大推动．实验和理论模拟均发现，在超强激光脉冲与等离子体相互作用过程中，可以产生高亮度、小尺寸、方向性好的高能质子束和高能重离子束．这种基于超强激光的高能离子源在先进离子束成像技术、惯性约束聚变混合“快点火”、新型台面离子加速器以及医疗等方面都有很诱人的应用前景．文章主要介绍了超强激光与固体靶相互作用中高能离子束（尤其是质子束）的加速机制、高能离子束特性、常用测量方法及其潜在应用，并对最新的研究进展进行了简单介绍．     

飞秒时间分辨光抽运探测技术及进展

文章简要介绍了飞秒时间分辨光抽运探测技术以及作者所在实验室的最新研究进展．灵敏度和信噪比是实验中的重要参数，文章着重介绍了作者在这两方面的改进，从而可检测到更微弱信号，并降低了使用的激光功率．配合具有光学窗口的液氦低温系统，还可对更多领域的材料进行研究，其中包括高温超导、生物化学样品和纳米材料等，并可给出物质内部结构等方面的重要信息．     

高分辨率X射线显微成像及其进展

介绍了高分辨率X射线显微成像产生背景和发展过程，着重分析了基于光学元件波带片的放大成像的基本原理，并简述了高分辨率三维成像的有关理论。同时给出国内外高分辨率X射线显微成像研究的最新进展，展望了高分辨率X射线显微成像的应用前景。     

Effect of the stagnation temperature on supersonic flow parameters: Application for air in nozzles

When the stagnation temperature of a perfect gas increases, the specific heats and their ratio do not remain constant any more and start to vary with this temperature. The gas remains perfect and its state equation always remains valid, except it will be called a calorically imperfect gas. The aim of this research is to develop the relations of the necessary thermodynamics and geometrical ratios and to study the supersonic flow at high temperature (lower than the threshold of dissociation). The results are found by the resolution of nonlinear algebraic equations and integration of complex analytical functions where the exact calculation is impossible. The dichotomy method is used to solve the nonlinear equation, and the Simpson algorithm is used for the numerical integration of the found integrals. A condensation of the nodes is used, since the functions to be integrated have a high gradient at the extremity of the interval of integration. A comparison is made with a calorifcally perfect gas to determine the error of this. An application is made for air in a supersonic nozzle. The text was submitted by the authors in English.     

Dendritic and eutectic growth in Sb<Subscript>60</Subscript>Ag<Subscript>20</Subscript>Cu<Subscript>20</Subscript> ternary alloy

The rapid solidification of Sb60Ag20Cu20 ternary alloy was realized by high undercooling method, and the maximum undercooling is up to 142 K (0.18TL). Within the wide undercooling range of 40-142 K, the solidified microstructures are composed of (Sb), θand ε phases. High undercooling enlarges the solute solubility of (Sb) phase, which causes its crystal lattice to expand and its crystal lattice constants to increase. Primary (Sb) phase grows in two modes at small undercoolings non-faceted dendrite growth is the main growth form; whereas at large undercoolings faceted dendrite growth takes the dominant place. The remarkable difference of crystal structures between (Sb) and θphases leads to (θ Sb) pseudobinary eutectic hard to form, whereas strips of θform when the alloy melt reaches the (θ Sb) pseudobinary eutectic line. The cooperative growth of θand ε phases contributes to the formation of (ε θ) pseudobinary eutectic easily. In addition, the crystallization route has been determined via microstructural characteristic analysis and DSC experiment.     

High‐pressure effects on the Diels–Alder reaction in room temperature ionic liquids

The effect of pressure on the Diels–Alder reaction was examined in room temperature ionic liquids, followed by high‐pressure FT‐IR spectroscopy using pressures up to 150 MPa. Pressure enhances the kinetic sensitivity of the reaction. The kinetic effect of fluorophobic interactions was examined using ionic liquids with fluorous cations. Ionic liquids in combination with ZnI₂ as a Lewis acid catalyst were also studied under high pressure. Copyright © 2007 John Wiley & Sons, Ltd.