棱镜-光栅-棱镜分光模块整体化设计及衍射特性分析

PGP模块是超光谱成像仪中重要分光器件。为了能够在制作前有效预测PGP整个系统的衍射效率分布及其衍射特性,提出了PGP整体化设计方法。从体位相全息光栅设计角度出发,结合棱镜与光栅各项参数的制约关系,编制了计算PGP整体衍射效率的分析软件,综合考察了棱镜与光栅各项参数对PGP模块衍射特性的影响,讨论了光栅布拉格波长的漂移特性,据此设计了一种用于成像光谱仪的宽波段高衍射效率PGP分光模块。模拟结果表明：棱镜1材料的色散系数越小,PGP的光谱带宽越窄;光栅布拉格波长的漂移增大了PGP模块和光栅的光谱带宽,带宽增大使光栅的角度选择性随之增大,拓宽了棱镜1材料的选择要求;棱镜1顶角、光栅的胶层厚度和相对介电常数调制度等参数是影响PGP衍射效率分布的重要因素,制作时需要精确控制。利用此方法设计的PGP分光模块在400～1 000 nm波段范围内衍射效率不低于50%,并给出具体设计参数,这对PGP制作具有一定的参考价值。     

Metal/semiconductor hybrids consisting of self-assembled CdS nanoparticles on Cd nanowires

We report on the synthesis and the characterisation of metal/semiconductor hybrids consisting of self-assembled CdS nanoparticles on Cd nanowires, which are grown by thermal evaporation of the mixture of CdS and Cr. The growth of the hybrids is attributed to the decomposition of CdS at high temperature and the strain relieving that arises mainly from the lattice mismatch between Cd and CdS. Temperature dependence of zero-field resistance of single nanohybrid indicates that the as-produced Cd/CdS nanohybrid undergoes a metal--semiconductor transition as a natural consequence of hybrid from metallic Cd and semiconducting CdS. The metal/semiconductor hybrid property provides a promising basis for the development of novel nanoelectronic devices.     

Nanohole 3D-size tailoring through polystyrene bead combustion during thin film deposition

A novel approach is presented for nanohole 3D-size tailoring. The process starts with a monolayer of polystyrene (PS) beads spun coat on silicon wafer as a template. The holes can be directly prepared through combustion of PS beads by oxygen plasma during metal or oxide thin film deposition. The incoming particles are prevented from adhering on PS beads by H₂O and CO₂ generated from the combustion of the PS beads. The hole depth generally depends on the film thickness. The hole diameter can be tailored by the PS bead size, film deposition rate, and also the combustion speed of the PS beads. In this work, a series of holes with depth of 4-24 nm and diameter of 10-36 nm has been successfully prepared. The hole wall materials can be selected from metals such as Au or Pt and oxides such as SiO₂ or Al₂O₃. These templates could be suitable for the preparation and characterization of novel nanodevices based on single quantum dots or single molecules, and could be extended to the studies of a wide range of coating materials and substrates with controlled hole depth and diameters.     

Room-temperature deposition of transparent conducting Al-doped ZnO films by RF magnetron sputtering method

Transparent conductive Al-doped zinc oxide (AZO) films with highly (0 0 2)-preferred orientation were deposited on quartz substrates at room temperature by RF magnetron sputtering. Optimization of deposition parameters was based on RF power, Ar pressure in the vacuum chamber, and distance between the target and substrate. The structural, electrical, and optical properties of the AZO thin films were investigated by X-ray diffraction, Hall measurement, and optical transmission spectroscopy. The 250 nm thickness AZO films with an electrical resistivity as low as 4.62 × 10⁻⁴ Ω cm and an average optical transmission of 93.7% in the visible range were obtained at RF power of 300 W, Ar flow rate of 30 sccm, and target distance of 7 cm. The optical bandgap depends on the deposition condition, and was in the range of 3.75-3.86 eV. These results make the possibility for light emitting diodes (LEDs) and solar cells with AZO films as transparent electrodes, especially using lift-off process to achieve the transparent electrode pattern transfer.     

光致变色二芳基乙烯抗疲劳特性实验研究

提出了一种简单直观的方法研究光致变色材料二芳基乙烯/PMMA膜的抗疲劳特性.通过测量样品在漂白和呈色过程中探测光的透过率,分析该样品光致变色过程的最佳曝光量,在此基础上测量样品的抗疲劳特性.结果显示:在漂白和呈色过程中,激发红光和紫光的最佳曝光量为分别为1 900 J/cm2和600 mJ/cm2,表明该材料对红光不敏感,对紫光比较敏感.定义漂白-呈色过程中,探测光透过率稳定值差下降为第一次循环的50%时样品已经疲劳.通过交替的漂白-呈色循环,测得这种二芳基乙烯材料的擦写次数为27次.     

A generalized Kolmogorov-Sinai-like entropy under Markov shifts in symbolic dynamics

In this paper, a generalized Kolmogorov-Sinai-like entropy ( entropy) in the sense of Tsallis is proposed with a nonextensive parameter q under Markov shifts, which contains the classical Kolmogorov-Sinai (KS) entropy and the Rényi entropy as well as Bernoulli shifts as special cases. To verify the formula of this entropy, a one-dimensional iterative system is chosen as an example of Markov shifts, and its entropy is evaluated by a new refinement method of symbolic dynamics called symbolic refinement which differs from the conventional numerical method. The numerical results show that this entropy is monotonically decreasing as q increases.     

基于水解活性的Zn2+荧光探针

合成了一种新颖的锌离子荧光探针N’(2-羟基苄基)-4-(2-羟基苯亚甲基胺)-苯甲酰肼(HHB),该探针本身的荧光较弱,但当它与Zn²⁺配位时荧光增强,在475 nm处产生一较宽的发射光谱,量子产率f=0.59 (λ_ex=370 nm)。该化合物对Zn²⁺具有良好的选择性能,环境生物体系中大量存在的碱金属和碱土金属离子K⁺,Na⁺,Mg²⁺和Ca²⁺以及过渡金属离子Mn²⁺,Co²⁺,Ni²⁺ 和 Cu²⁺ 等对Zn²⁺的检测没有明显影响。在生命体系的pH值范围(6.8~7.7),配合物HHB显示出对Zn²⁺检测较高的灵敏度。作为比较文中还研究了HHB水解的主要产物4-氨基苄腙-水杨醛(HB)对Zn²⁺的识别与传感性能。     

FTIR结合生理特性研究镉胁迫对果灰藓的影响

苔藓植物可作为监测环境中重金属污染的指示植物。以苔藓植物果灰藓为实验材料,用不同浓度的重金属镉处理7 d后,借助傅里叶红外光谱法(FTIR)分析重金属镉胁迫下果灰藓各化学成分的变化,同时测定可溶性糖(SS)、可溶性蛋白(Pr)、丙二醛(MDA)含量在镉胁迫下的生理指标。结果表明：随着镉处理浓度的升高,可溶性糖含量和可溶性蛋白含量呈现先上升后下降的趋势,丙二醛含量先下降后上升。FTIR与果灰藓响应重金属镉胁迫的各生理指标变化趋势较一致,且FTIR比传统的生理指标测定更敏感、便捷。因此,FTIR可以作为研究苔藓植物应用于环境重金属污染监测的一种快速、有效的方法。     

1．06μm激光大气后向散射强度仿真计算研究

针对激光大气后向散射信号对激光导引头制导性能的影响,分析了激光大气后向散射的形成,利用MATLAB语言对1．06μm激光大气后向散射信号强度进行了仿真计算,同时设计开发了一套模拟计算软件,并通过试验验证了软件计算激光大气后向散射信号强度的准确性。