Formation of 10-30 nm SiO2/Si structure with a uniform thickness at ∼120 °C by nitric acid oxidation method

Silicon dioxide (SiO₂) layers with a thickness more than 10 nm can be formed at ∼120 °C by direct Si oxidation with nitric acid (HNO₃). Si is initially immersed in 40 wt.% HNO₃ at the boiling temperature of 108 °C, which forms a ∼1 nm SiO₂ layer, and the immersion is continued after reaching the azeotropic point (i.e., 68 wt.% HNO₃ at 121 °C), resulting in an increase in the SiO₂ thickness. The nitric acid oxidation rates are the same for (1 1 1) and (1 0 0) orientations, and n-type and p-type Si wafers. The oxidation rate is constant at least up to 15 nm SiO₂ thickness (i.e., 1.5 nm/h for single crystalline Si and 3.4 nm/h for polycrystalline Si (poly-Si)), indicating that the interfacial reaction is the rate-determining step. SiO₂ layers with a uniform thickness are formed even on a rough surface of poly-Si thin film.     

40Ar+诱导无定形碳到金刚石纳米晶相变的研究

通过60 keV的⁴⁰Ar⁺辐照无定形碳靶合成了大量尺寸不同的金刚石纳米颗粒.高分辨透射电子显微镜配合能量色散X射线谱和电子衍射以及Raman谱分析的结果表明，这些嵌于具有扰动石墨结构薄膜中的纳米金刚石颗粒，其成核率很高(约为10¹³/cm²)，而且可以生长到较大的尺寸，有的甚至可以达到微米量级.对其相转变过程也进行了初步探讨. 关键词： 离子束 金刚石纳米晶 相变 透射电子显微镜     

高功率横流CO2激光器高反膜耦合窗口ZnSe热形变理论和实验研究

给出高功率横流ＣＯ２激光器高反膜红外膜红外耦合窗口ＺｎＳｅ的热形变理论和实验。在合理近似条件下，导出ＺｎＳｅ窗口温度分布和热形变的理论表达式。理论和实验相符。     

空间光通信指令传输的抗干扰设计

设计一种用归零码及多重相关解调技术的传输方案，并给了所需的几种抗干扰单元电路，最后结合实验说明了此方案可提高不良环境下传输数据的置信率。     

应用波分复用改善像束传像系统像质的研究

本文通过分析空间波分复用系统中包散元件的色散平均效应,用线扩散传递函数研究了像束传像性质,由光学成像的本征理论用像束成像信息量分析了波分复用改善像束传像像质的机制,并从实验上验证了上述分析结论.     

TE mode coupling between end separated buried waveguides: expressions and calculations

In this paper the power coupling expression between two identical axially aligned and spatially separated waveguides is presented. Calculations using the coupling expression for a Gaussian mode profile in the input waveguide produce results that are in excellent agreement with experimental observations.     

Dependence of the refractive power of Nd:YAG rods on the intracavity intensity

The refractive power of two flashlamp-pumped Nd:YAG rods was measured as being dependent on the output coupling of the resonator. With laser oscillation, the refractive power or thermal heat is decreased by up to 15% and a minimum occurs at a specific output coupling. The experimental results could be explained by a theoretical model assuming a non-radiative transition from the upper laser level to the ground state. The lifetime of this non-radiative transition decreases with increasing pumping power per pulse and, for pumping power higher than 100 kW, saturation at a value of 0.63 times the fluorescence lifetime occurs. The results indicate that the non-radiative process is caused by energy migration to flashlamp-induced transient quenching centres.     

Nucleophilic Solvent Intervention in Benzylic Solvolyses. The Use of YBnx Scales in Grunwald-Winstein Type Correlation Analysis

New Y_BnX scales of solvent ionizing power are developed and considered superior to Y_x scales for benzylic bromides, chlorides, p-nitrobenzoates and tosylates in Grunwald-Winstein type correlation analysis of solvolytic reactivities. The Y_BnX values, with addition and revision, are summarized. Evidence for nucleophilic solvent intervention in the solvolysis transition state for secondary and tertiary benzylic substrates is given. The advantages of employing this tool to understand solvolysis mechanisms are discussed.     

带调速器的多台机组的暂态关联稳定性

对于带调速器的多台电机组,本文引入关联矩阵E=(e_(ij))_(n×n),应用李雅普诺夫函数分解法,研究了此电力大系统的暂态关联稳定性,得到了系统的分解系数与稳定区域的估计公式。     

人力资源的预测方法

人力资源规划是必不可少的管理环节．科学的人力资源规划，必须建立在对人员供、需的准确预测的基础上．本文讨论人力资源预测的问题和转移矩阵等方法的使用．