H^＋注入锗酸铋晶体表面层的性质

Ｈ＾＋注入锗酸铋（Ｂｉ４Ｇｅ３Ｏ１２或ＢＧＯ）晶体引起某些效应，如辐射损伤，光学吸收和近表层区域的晶体分解。经Ｈ＾＋注入后，ＢＧＯ晶体的颜色变成棕色，但实验中证实不了该变化是由色心的产生所引起。此外，实验中也示观察到Ｈ＾＋注入ＢＧＯ晶体中有离子束诱发的光学活性变化。可见在注入过程中，未发生从Ｂｉ４Ｇｅ３Ｏ１２转变到Ｂｉ１２ＧｅＯ２０的结构相变，由此预见，注入过程中可能发生离子束引起的晶体分解。Ｈ＾     

任意二次型双曲面扁薄壳的基本解

本文对任意二次型双曲面扁薄壳的八阶偏微分方程采用平面波分解和小参数法导出了它的基本解。 在基本解的基础上,本文还得出边界为无限大时薄壳在集中荷载作用下的格林函数,适用于以边界积分方程法来分析具有任意边界条件的这类薄壳结构在任意荷载作用下的位移与内力,与一般有限单元法相比,它能较大的地节省计算机的内存和缩短分析时间。     

电子产品的模糊随机统计

电子产品,如电视机、收音机、录音机等,都是由成千上万个元器件组成的每一种元器件都有好或坏的问题.为了保证最终产品的质量,工厂从设计、生产到销售的各个环节,都有严格的质量管理制度,从而也日复一日、年复一年地进行着大量的统计.传统的统计方法和理论是建立在事件的随机性上的,但客观事物往往还有“模糊性”的一面. 一、模糊概率的概念 传统的概率论只研究事件的随机性.如某生产流水线的合格品率是99%,即任意抽取一件产品,有99%的可能抽到合格品.这里,“事件”是确定的。抽到合格品,但事件的出现与否是不确定的:有99%的可能出现,也有1%…     

NORMAL COORDINATE TREATMENT OF COMPLEXES OF LANTHANIDE NITRATES WITH CROWN ETHER

In this paper, by using point mass model, the normal coordinate lanalysis calculations of La(15-C-5) (NO_3~-)_3 and La (18-C-6) (NO_3~-)_3 are performed to give theoretical results in agreement with frequencies and intensities of infrared and Raman bands. In the calculations, the same force constants with respect to the two molecules are adopted and some internal coordinates which are less important are neglected. Furthermore, the properties of coordination bonds, approximation calculation method and other related problems are discussed.     

稀土复合氧化物催化剂中镧、钙、锰的测定

稀土复合氧化物催化剂中镧、钙、锰的含量分析,目前,已有人做过工作。方法之一,控制pH分离镧、锰后,用EDTA络合滴定钙的含量,再在磷酸介质中用硫酸亚铁法分析锰量,差减法计算镧的含量;方法之二,利用离子交换法分离镧、钙、锰,再采用络合滴定分别测镧、钙、锰含量。两种方法共同存在的问题是手续冗长,费时。其中方法     

单晶Cu(001)薄膜塑性变形的分子动力学模拟

使用分子动力学方法,模拟研究了单晶Cu(001)薄膜在双向等轴拉伸应变下的塑性变形行为.当应变超过一定值时,样品通过产生位错、层错及孪晶而发生塑性变形.当应变相对较低时,不全位错首先在薄膜表面形核并在密排面上滑移,留下堆积层错;当应变增加时,位错在表面与内部同时成核生长,层错数量也随之增加.分析了相邻滑移面上的位错之间相互作用形成孪晶的微观过程.材料内部形成大量堆积层错及孪晶后,较大孪晶的密排面上的原子也会发生滑移,形成孪晶内部的层错结构以释放残余应力.     

SiO2保护膜对高反膜激光损伤特性的改善

 为了研究高功率系统中高反膜的损伤机制,对高功率系统中最常用的基频高反膜进行了损伤实验。利用台阶仪、扫描电镜、表面轮廓仪等手段,对实验样品的典型损伤形貌进行了比较和分析。结果表明：保护膜的存在增强了样品的抗激光损伤能力;未加保护膜样品的典型破坏形貌是由材料热物特性差异导致的分层剥落损伤,这类损伤在后续的脉冲辐照下会迅速发展;有保护膜样品的典型破坏形貌是中心带有μm量级小坑的等离子体烧蚀损伤区,其主要是由缺陷受热力作用喷溅导致,小坑附近膜面的凸起是这种力学作用的宏观体现,这类损伤在后续的脉冲辐照中表现得相对比较稳定。保护膜的存在,在一定程度上抑制了分层剥落这种灾难性损伤的出现,改善了样品的损伤特性。     

Improving the precision of fluorescence lifetime measurement using a streak camera

Streak camera has high temporal resolution and high sensitivity, and is a powerful tool in biomedical study to measure fluorescence lifetime and perform fluorescence lifetime imaging. However, nonuniformity of the gain in the streak tube and nonlinearity of the sweeping speed limit the precision of fluorescence lifetime measurement, particularly when fluorescence lifetimes are short. We have constructed a two-photon excitation fluorescence lifetime measurement system that is based on a synchroscan streak camera and have developed accordingly a method to correct the effect of gain nonuniformity and nonlinearity of sweeping speed on the measurement precision. A continuous-wave laser of high stability is used to calibrate the gain of the streak camera, and a Fabry-Perot etalon is used to calibrate the nonlinearity of the sweeping speed. Fitting algorithms are used to correct the gain of the streak camera and nonlinearity of the sweeping speed respectively, which significantly improves the measurement precision of the system, as characterized through the fluorescence lifetime of the short-lived fluorescence dye, Rose Bengal. Experimental results show that the measurement fluctuation of the lifetime has been improved from more than 10% to 2% after correcting the effects of gain nonuniformity and sweeping speed nonlinearity.     

Laser Damage Mechanisms of Amorphous Ta2O5 Films at 1064, 532 and 355nm in One-on-One Regime

Ta2O5 films are deposited on fused silica substrates by conventional e-beam evaporation. Surface topography and chemical composition are examined by atomic force microscopy （AFM） and x-ray photoelectron spectroscopy （XPS）. The calculation of electron structures of Ta2O5 and Ta2O5-x is attempted using a first-principle pseudopotential method within the local density approximation. The laser-induced damage threshold （LIDT） is performed at 1064, 532 and 355 nm in 1-on-1 regime, respectively. The results show that the LIDT increases with the wavelength increasing, which is in agreement with the wavelength effect. However, the LIDT results are not consistent with the empirical equation （I（λ）=aλm）, which may be attributed to the intrinsic absorption of Ta2O5 at the wavelengths of 532 or/and 355 nm. Moreover, different damage morphologies are observed when the films are irradiated at different wavelengths. It is concluded that the laser damage at 1064 nm is the defect dominant mechanism and at 355 nm it is the intrinsic absorption dominant mechanism, whereas at 532 nm it is the combined defect and intrinsic absorption dominant mechanism.