RuH2和RuN2电子组态与光谱性质的从头计算

用量子化学从头算方法在B3LYP/6 311G 的水平上 ,研究了RuH2 和RuN2 可能的电子组态和光谱性质 .结果表明 ,RuH2 的3 B2 和5Σ-态对应于静电作用的物理吸附态 .RuN2 的一重态和三重态的计算结果跟钌单晶面上的实验值相接近 .而RuN2 在C∞v对称性时 ,五重态5Σ-的计算频率比实验值稍低 .在C2v对称性时 ,五重态的计算频率值则更低 ,3 B2 和5A1态不能稳定存在     

Room-temperature anomalous Hall effect and magnetroresistance in (Ga, Co)-codoped ZnO diluted magnetic semiconductor films

This paper reports that the(Ga,Co)-codoped ZnO thin films have been grown by inductively coupled plasma enhanced physical vapour deposition.Room-temperature ferromagnetism is observed for the as-grown thin films.The x-ray absorption fine structure characterization reveals that Co 2+ and Ga 3+ ions substitute for Zn 2+ ions in the ZnO lattice and exclude the possibility of extrinsic ferromagnetism origin.The ferromagnetic(Ga,Co)-codoped ZnO thin films exhibit carrier concentration dependent anomalous Hall effect and positive magnetoresistance at room temperature.The mechanism of anomalous Hall effect and magneto-transport in ferromagnetic ZnO-based diluted magnetic semiconductors is discussed.     

一种新型径向三腔同轴虚阴极振荡器全三维粒子模拟研究

提出了一种新型径向三腔同轴虚阴极振荡器,并进行了数值模拟研究. 研究表明: 这种径向三腔结构在束波转换面进行电场调制,能够大幅提高束波转换效率;同时,由阳极栅网和径向三腔结构构成的谐振装置能有效地抑制模式竞争;另外,由于采用了同轴引出结构,在提高能量引出的同时还能有效吸收漂移管中被利用过的电子,因此这种新型虚阴极振荡器能够获得较高的输出功率. 模拟的电子束电压为400 kV,电流为50 kA,主频为4.5 GHz,峰值功率达到6 GW,平均输出功率为3.1 GW,束波转换效率达到15%. 关键词： 高功率微波 同轴虚阴极振荡器 粒子模拟 束波转换效率     

基于波数均匀展宽模型的全反射傅里叶变换成像光谱仪高精度光谱定标处理方法

全反射傅里叶变换成像光谱仪ARFTIS(all-reflection Fourier transform imaging spectrometer)是基于FT成像光谱理论的一种新型仪器,它不但具有高光谱分辨率特点,而且还具有宽波段、无色差的特点,特别适合应用在宽波段成像的遥感领域.目前常用的光谱定标方法有单色法、平均法...     

Optoacoustic imaging with synthetic aperture focusing and coherence weighting

Optoacoustic imaging takes advantage of high optical contrast and low acoustic scattering and has found several biomedical applications. In the common backward mode a laser beam illuminates the image object, and an acoustic transducer located on the same side as the laser beam detects the optoacoustic signal produced by thermoelastic effects. A cross-sectional image is formed by laterally scanning the laser beam and the transducer. Although the laser beam width is generally narrow to provide good lateral resolution, strong optical scattering in tissue broadens the optical illumination pattern and thus degrades the lateral resolution. To solve this problem, a combination of the synthetic aperture focusing technique with coherence weighting is proposed. This method synthesizes a large aperture by summing properly delayed signals received at different positions. The focusing quality is further improved by using the signal coherence as an image quality index. A phantom comprising hair threads in a 1% milk solution was imaged with an optoacoustic imaging system. The results show that the proposed technique improved lateral resolution by 400-800% and the signal-to-noise ratio by 7-23 dB over conventional techniques.     

单光子量子密钥分发系统中干涉稳定性分析

为了研究位相编码量子密钥分发系统中的干涉稳定性, 运用解析和数值计算方法详细研究了光纤双折射、温度变化、非对称性以及耦合器分光比对量子密钥分发系统干涉条纹可见度的影响, 结果表明光纤双折射、温度变化和非对称性都将影响系统的干涉可见度, 调整接收端的调制位相能消除温度变化的影响, 并减小非对称性对系统的影响, 但不能改善光纤双折射对系统干涉的影响. 另外, 耦合器分光比影响系统的效率.     

Synthesis and Raman analysis of 1D-ZnO nanostructure via vapor phase growth

1D-nanostructural zinc oxide (ZnO) with different shapes have been synthesized on p-type Si(1 0 0) and glass substrates via vapor phase growth by heating pure zinc powder at temperatures between 480 and 570 °C. The different ZnO nanostructures depend on the substrates and the growth temperatures. Scanning electron microscopy and X-ray diffraction revealed that a well-aligned nanowires array, which are vertical to the substrate of Si(1 0 0) with 18 sides on their heads, but six sides on their stems, has been formed at 480 °C. Raman study on the ZnO nanostructures shows that the coupling strength between electron and phonon determined by the ratio of the second- to the first-order Raman scattering cross-sections declines with decreasing diameter of the nanowires. However, a little changes of the coupling strength in terms of the width of the nanobelts have been observed.     

非晶/微晶相变域硅薄膜及其太阳能电池

采用甚高频等离子体增强化学气相沉积（VHF-PECVD）法，成功制备出从非晶到微晶过渡区 域的硅薄膜. 样品的微结构、光电特性及光致变化的测量结果表明这些处于相变域的硅薄膜 兼具非晶硅优良的光电性质和微晶硅的稳定性. 用这种两相结构的材料作为本征层制备了p- i-n太阳能电池，并测量了其稳定性. 结果在AM15(100mW/cm²) 的光强下曝光 800—5000min后，开路电压略有升高，转换效率仅衰退了29%. 关键词： 相变域硅薄膜 光电特性 太阳能电池     

非晶/微晶两相硅薄膜电池的计算机模拟

在对不同晶相比硅薄膜的实验研究的基础上，利用有效介质理论估算了这种两相材料的光吸 收系数、迁移率寿命乘积及带隙宽度等参量，计算机模拟了不同结晶比硅薄膜电池的伏安特 性及光谱响应；结果为随着本征层微晶成分的增多，电池的开路电压逐渐减小，短路电流逐 渐增大，本征层的最佳厚度逐渐增大，填充因子有降低的趋势，电池的效率随晶相比的增大 而减小. 电池的光谱响应曲线表明，随晶相比的增大电池的长波响应明显提高. 根据这些模 拟结果，分析讨论了在考虑Lambertian背反射的情况下，非晶/微晶叠层电池的底电池采用 晶相比为40％—50％的两相硅薄膜材料做本征层是最佳选择. 关键词： 两相硅薄膜 太阳能电池 计算机模拟     

Ablation of Transparent Materials Using Excimer Lasers for Photonic Applications

For many years, the development of effective ablation or laser machining techniques for making micro-optical components has been the key factor in the birth of new photonic devices and systems. In this article, the ablation characteristics of two types of the most important transparent materials, transparent polymers and glasses, are studied. Simple shaped microcavities are first machined for studying the fundamental ablation parameters, including threshold fluence, effective absorption coefficient, and ablation rate. In studying polymer ablation, five standard grades and five proprietary polymeric compounds are selected. Ablation techniques using these transparent polymers for making arrayed ferrules and curved microlenses are presented. Applications of these ablated microstructures for optical fiber connectors, optical fiber coupling and alignment, and transparent chip encapsulants, are introduced and demonstrated with emphasis on the quality of the ablated profiles and dimensions to satisfy the required performance. In glass ablation, borosilicate glasses are considered and their associated ablation behaviors are studied. The procedures to ablate glass-based arrayed microstructures with flat and curved surfaces are described. The utilizations of these arrayed microstructures for optical waveguide, wave absorber, and beam guider, are specifically discussed. Finally, concluding remakes for future trends are presented.