Pinhole defects in MPCVD diamond films

Diamond films were deposited in microwave plasma chemical vapor deposition (MPCVD) method on plain silicon substrates with (100) orientation. And the pinhole defects on them were investigated by optical microscopy and scanning electron microscopy (SEM). X-ray masks were fabricated with the films deposited by us. We found the pinhole defects in the film destroyed the gold absorber. The corrosion-resistance tests conducted in 30% KOH solution under 80℃showed that the diamond films with pinhole defects have lower corrosion-resistance. In addition, the possible mechanism of the formation of pinhole defects in diamond films was discussed. And we deduced that the defects on substrates, competitive growth of multi-phase in diamond films, lattice dislocation between substrates and diamond films could be associated with the defect formation.     

高In组分InxGa1－xN/GaN多量子阱材料电致荧光谱的研究

研究了高In组分In_xGa_1-xN/GaN（x≈30%）多量子阱（MQWs）结构 发光二极管样品在不同注入电流下的电致荧光（EL）谱及反常的双峰现象.结果表明：有源区 内建电场在外界电流注入条件下逐渐受屏蔽，这一效应在高In组分In_xGa_{1 -x}N/GaN MQWs材料的发光复合机理中占有重要地位. 关键词： xGa_1-xN/GaN多量子阱')" href="#">In_xGa_1-xN/GaN多量子阱 电致荧光谱 内建电场     

ZrO2/SiO2多层膜中膜厚组合周期数及基底材料对残余应力的影响

ZrO2/SiO2多层膜由相同沉积条件下的电子束蒸发方法制备而成,通过改变多层膜中高(ZrO2)、低(SiO2)折射率材料膜厚组合周期数的方法,研究了沉积在熔石英和BK7玻璃基底上多层膜中残余应力的变化.用ZYGO光学干涉仪测量了基底镀膜前后曲率半径的变化,并确定了薄膜中的残余应力.结果发现,该多层膜中的残余应力为压应力,随着薄膜中膜厚组合周期数的增加,压应力值逐渐减小.而且在相同条件下,石英基底上所沉积多层膜中的压应力值要小于BK7玻璃基底上所沉积多层膜中的压应力值.用x射线衍射技术测量分析了膜厚组合周期数不同的ZrO2/SiO2多层膜微结构,发现随着周期数增加,多层膜的结晶程度增强.同时多层膜的微结构应变表现出了与所测应力不一致的变化趋势,这主要是由多层膜中,膜层界面之间复杂的相互作用引起的.     

蒸气发生–原子荧光法连续测定化探样品中微量砷、锑、铋、汞、硒、碲

建立了连续测定化探样品中微量砷、锑、铋、汞、硒、碲的原子荧光光谱法。研究了酸度、KBH4溶液浓度、基体改进剂等条件对荧光强度的影响。在优化的实验条件下,砷、锑、铋、汞、硒、碲的检出限分别为0.011,0.006,0.020,0.002 5,0.005,0.002 mg/L,测定结果的相对标准偏差分别为1.30%,4.64%,3.76%,5.46%,2.04%,3.41%(n=11),准确度大于98%。该方法简便,成本低,检测结果准确,检出限、准确度及精密度均能达到行业规范要求,可用于化探样品中微量元素测试。     

Interval finite element method and its application on anti-slide stability analysis

The problem of interval correlation results in interval extension is discussed by the relationship of interval-valued functions and real-valued functions. The methods of reducing interval extension are given. Based on the ideas of the paper, the formulas of sub-interval perturbed finite element method based on the elements are given. The sub-interval amount is discussed and the approximate computation formula is given. At the same time, the computational precision is discussed and some measures of improving computational efficiency are given. Finally, based on sub-interval perturbed finite element method and anti-slide stability analysis method, the formula for computing the bounds of stability factor is given. It provides a basis for estimating and evaluating reasonably anti-slide stability of structures.     

发挥作业价值 实现教学相长

作业是沟通“教”与“学”的纽带,其在数学教学中的地位是毋容置疑的.为了更好地发挥作业在提升学习质量、强化知识理解、构建知识体系等方面的价值,教师在作业设计上要控制好“度”,把握好“质”,借助作业反馈及时调整教学策略,进而实现减负增效、教学相长.     

光致温度场光镊：原理及生物医学应用

面向生物粒子操控方法的研究,在生物医学和生命科学等领域具有重要意义。光镊操控具有无接触与高精度的特点,已被广泛应用于多个领域的研究中。然而,传统光镊的光热效应以及衍射极限都制约着光镊在生物医学领域的更广泛应用和发展。近十年来,研究者们将光热效应化劣势为优势,利用光与热的耦合效应实现了多种粒子的精确捕获及操控,即光致温度场光镊（OTFT）。由于此种新型光镊对光能的利用率极高,能量密度低于传统光镊近3个数量级,并可实现颗粒的大范围操控,极大地拓展了光镊可操控粒子的种类,已经成为纳米技术以及生命科学领域的重要研究工具。温度场光镊仍面临诸多问题,例如对于颗粒界面调控的依赖性以及三维捕获受限等,尤其是在生物光子学的研究中,还需要进一步发展和优化。本文对光致温度场光镊操控基本原理及其在生物医学中的应用两个方面进行了系统阐述,并对其今后的发展与挑战进行了展望。     

基于二维吸收光谱重建的数值迭代算法的比较

基于可调谐激光吸收光谱的二维温度和浓度分布重建对于燃烧诊断具有重要意义,而数值迭代算法在温度和组分浓度的重建中起着重要作用。通过对比发现自适应迭代算法和最小二乘QR分解算法对于重建二维温度和气体浓度分布具有很好的优势。研究表明,波长7 154.35, 7 153.75, 7 185.60和7 444.36 cm^-1四条H₂O的吸收谱线,非常适合测量高温预混火焰中的温度和水蒸气浓度分布。与7 444.36, 7 185.60, 7 154.35和7 153.75 cm^-1处的吸收谱线相比,CO₂和CH₄的光谱吸光非常微弱,在该波段O₂和CO基本没有吸收,因此燃烧环境中CO₂, CH₄, O₂和CO等气体对于H₂O吸收谱线基本没有影响。通过比较不同算法的最优松弛因子、计算时间和重建误差等,发现与最小二乘QR分解算法相比,自适应迭代算法具有更好的重建质量和更短的计算时间。在自...     

杆系结构系统失效模式识别的几何法及其应用

在结构可靠性分析中,由于外载、材料性能参数等的随机性,在所有可能的失效模式中,必有少数几个失效模式其出现概率比其他失效模式要大得多,因此求取这为数不多的临界失效模式就是结构系统可靠性分析中一个主要课题.本文提出了求取杆系结构系统失效模式(即机构)的几何法.它是从几何方程出发,求得一机构,然后在此机构的基础上经过简单的矩阵相加.相乘就可得到其他机构.同时采用比例加载乘子λ这一物理意义明潦的参数来作为判别是否为临界机构的准则,效果很好.算例表明了此法的可行性,有效性.     

Characteristics of 355 nm Laser Damage in KDP and DKDP Crystals

We present the characteristics of bulk damage induced by the third harmonic of Nd：YAG laser irradiation in KDP and DKDP crystals. Bulk damage occurs as a few or a series of pinpoints consisting of a core and the deforming zone. The results of a 1-on-1 test reveal that the pinpoint size increases with incvreasing fluence, and the pinpoint density increases exponentially with increasing fluence. The results of an s-on-1 test indicate that the pinpoint density increases gradually with laser pulse number, but the size does not grow. These results are consistent with a model in which nanoabsorbers are assumed to exist in the crystal and the initiation of damage is determined by heating them to the critical temperature.