CdTe量子点与罗丹明B水溶液体系下的双光子激发荧光共振能量转移

采用时间分辨荧光光谱技术研究了在双光子激发下不同尺寸的量子点与罗丹明B 之间的荧光共振能量转移. 研究结果表明, 在800 nm的双光子激发条件下, 体系间能量转移效率随着供体吸收光谱与受体荧光光谱的光谱重叠程度增加而增加; 理论分析表明, 供体和受体间的Förster半径增加是导致其双光子能量转移效率增大的物理原因. 同时, 研究了罗丹明B浓度对荧光共振能量转移效率的影响. 研究结果表明, 量子点的荧光寿命随着罗丹明B浓度的增加而减小; 量子点与罗丹明B之间的荧光共振能量转移效率随着罗丹明B浓度的增加而增加; 当罗丹明B浓度为3.0×10^-5 mol·L^-1时, 双光子荧光共振能量转移效率为40.1%.     

Al_2O_3+PTFE(+PPS)复合材料滑动摩擦磨损的研究

作者采用冷压-烧结工艺研制了Al_2O_3+PTFE、PTFE+PPS和Al_2O_3+(PTFE+PPS)3类复合材料,并对这些材料的摩擦磨损行为及其磨损机理进行了研究。结果表明,适量Al_2O_3粒子的弥散可以明显提高复合材料的耐磨性,PTFE+PPS复合材料的耐磨性远比PTFE的好,摩擦系数几乎与PTFE的相同,是一种良好的减摩抗磨材料。复合材料的磨损过程主要受粘着、犁削和塑性流动机制的控制。     

Synthesis,Structure and Elastic Properties of a New Hybrid Perovskite Material: [C6H14N2]KBr3

A new hybrid organic-inorganic perovskite(HOIP)material,[C6H14N2]KBr3,has been synthesized via hydrothermal method and fully characterized.[C6H14N2]KBr3 has a three-dimensional perovskite structure and crystalizes in a trigonal P3121 space group.The elastic properties of[C6H14N2]KBr3 were fully calculated via the density functional theory calculations,which reveal the elastic moduli(11.54~14.07 GPa),shear moduli(4.56~5.68 GPa),Poisson’s ratios(0.18~0.32),bulk modulus(8.51 GPa)and acoustic velocity(2.57~2.74 kms^-1).Additional nanoindentation experiments in the form of single-crystals confirmed the validity of our theoretical approach.[C6H14N2]KBr3 exhibits higher stiffness and thermal stability than the well-known photovoltaic CH3NH3PbI3,which makes it worthwhile for exploring optoelectronic properties.     

Temporal response of laminated graded-bandgap GaAs-based photocathode with distributed Bragg reflection structure: Model and simulation

To describe the dynamic response characteristics of the laminated graded-bandgap GaAs-based photocathode with distributed Bragg reflection structure, a general theoretical temporal response model is deduced by combining the unsteady continuity equation and numerical calculation method. Through the model, the contribution of the distribution Bragg reflection structure and graded-bandgap emission layer to the temporal response are investigated. Meanwhile, the relationships between the temporal response characteristics of the laminated GaAs-based photocathode and different structural parameters are also analyzed, including average electron decay time, emission layer thickness, and incident light wavelength. It is found that the introduction of distribution Bragg reflection (DBR) layer solves the discrepancy between the absorption capability of the emission layer and the temporal response. Moreover, the distributed Bragg reflection layer can improve the time response by optimizing the initial photoelectron distribution. The improvement effect of the DBR layer on the temporal response is enhanced with the emission layer thickness decreasing or the incident light wavelength increasing. These results explain the effect of the DBR layer of the photocathode on the dynamic characteristics, which can offer a new insight into the dynamic research of GaAs-based photocathode.     

带超环面镜的掠入射光栅谱仪测试系统响应特性模拟分析

指出了文献[1]在物理概念上和公式推导中的错误,并在订正了这些错误之后,考虑了实际的激光等离子体光源的几何尺度和线状等离子体的安排,对在复合泵浦X激光增益实验中所使用的带超环面镜X光中继元件的掠入射光栅光谱仪系统进行了全面的模拟计算.结果表明,作者所使用的带超环面镜的X光增益测试系统,其因离焦而导致的非线性效应是完全可以忽略的,系统的空间分辨能力的下降也是非常小的,从而否定了文献[1]中的结论,表明作者在X激光增益测量实验中所使用的带超环面镜X光中继元件的掠入射光栅光谱仪系统是完全可靠的.     

聚氯乙烯—吡啶树脂的合成及其催化水解反应的研究

在浓氧氢氧化钠作用下，聚氯乙烯与吡啶作用与制成聚氯乙烯－吡啶树脂，测定了其元素组成和红外光谱，并考察了其在酯水解反就听催化活性。     

杯电極溶液法光谱光源中物质蒸发与弧温的研究

杯电极溶液电弧法无论应用在金属或非金属样品的光谱分析中,都受到光谱工作者们越来越多的注意。为了更进一步提高它的分析灵敏度和准确度,作者们对它的蒸发激发机构进行了研究。在燃弧过程中,曾观察到弧区是由弧焰与弧柱两个部分组成的。通过一系列实验发现:弧焰的存在直接影响到溶液样品的蒸发,而弧柱在光谱的激发过程中起着主导的作用。此外还利用OH带光谱测量弧焰及弧柱的温度分布。从得到的结果中找到提高分析灵敏度和准确度的途径。     

飞秒激光烧蚀LiNbO3晶体的形貌特征与机理研究

采用了不同能量的单脉冲和多脉冲飞秒激光对LiNbO₃晶体进行烧蚀，并刻蚀了表面衍射型光栅.通过扫描电镜和原子力显微镜观察了烧蚀点的形貌特征，首次发现利用单束飞秒激光脉冲对LiNbO₃晶体烧蚀，可以得到超衍射极限的烧蚀点，当聚焦光斑直径约为2μm、能量为170nJ的单脉冲飞秒激光作用时，烧蚀点的直径约为400nm，100nJ，17个脉冲作用时烧蚀点的直径约为800nm.同时可以观察到在能量较低的多脉冲飞秒激光作用下， LiNbO₃晶体呈现出大约200nm周期性分布的波纹状结构.实验结果表明，选择合适参数的飞秒激光脉冲可以对LiNbO₃晶体进行超衍射极限加工，这对于利用飞秒激光制作LiNbO₃基质的微纳光电子器件有十分重要的意义.     

金纳米颗粒的有序制备及其光学特性

采用纳米球蚀刻技术在石英衬底上制备了不同高度的金纳米颗粒阵列.通过扫描电子显微镜对其表面形貌进行了观测,表明金纳米颗粒为有序分布的三棱柱结构.通过红外—紫外吸收光谱仪在190—900nm波长范围内对其光吸收特性进行了测量, 并成功观测到了金纳米颗粒表面等离子体振荡效应引起的光吸收峰,结果表明随着金纳米颗粒高度的增加,其吸收峰的位置向短波方向移动(蓝移).同时对金纳米颗粒的光吸收特性进行了基于离散偶极子近似的理论计算,并与实验结果进行了比较. 关键词： 纳米球蚀刻技术 金纳米颗粒 离散偶极子近似     

Angular momentum distribution in strong-field frustrated tunneling ionization

Using the classical-trajectory Monte Carlo model, we have theoretically studied the angular momentum distribution of frustrated tunneling ionization(FTI) of atoms in strong laser fields. Our results show that the angular momentum distribution of the FTI events exhibits a double-hump structure. With this classical model, we back traced the tunneling coordinates, i.e., the tunneling time and initial transverse momentum at tunneling ionization. It is shown that for the events tunneling ionized at the rising edge of the electric field,the final angular momentum exhibits a strong dependence on the initial transverse momentum at tunneling.While for the events ionized at the falling edge, there is a relatively harder recollision between the returning electron and the parent ion, leading to the angular momentum losing the correlation with the initial transverse momentum. Our study suggests that the angular momentum of the FTI events could be manipulated by controlling the initial coordinates of the tunneling ionization.