裂解温度对CVD法制备多壁碳纳米管的影响

用SEM、TEM、HRTEM及拉曼光谱方法研究了催化裂解乙炔制备多壁碳纳米管过程中裂解温度的影响,结果表明,在650℃～700℃裂解乙炔,可获得产量高、直径分布均匀、石墨程度高的多壁碳纳米管,并对裂解温度影响机制进行了分析和探讨。     

一种复合型空间软X射线--极紫外波段望远镜设计

根据空间对日观测的需要,提出了一种复合型宽波段范围的软X射线———极紫外望远镜的设计方案。该望远镜是把小结构尺寸的卡塞格林型极紫外波段正入射望远镜放置在软X射线波段,并由常用的Wolter Ⅰ型掠入射望远镜的中心部分组成。在软X射线和极紫外波段具有相同的焦距和视场角,共同使用同一个探测器,外形尺寸与相同指标的掠入射型望远镜一致,且在极紫外波段具有较高的角分辨率和光谱分辨率,适合于在空间进行对日观测使用。     

Comparative study of spectroscopic properties of Er^3＋／Yb^3＋-codoped tellurite glass and fibres under 980nm excitation＊

A tellurite fibre of TeO_{2}－ZnO－La_{2}O_{3}－Li_{2}O glass codoped with 20000 ppm ytterbium and 5000 ppm erbium was fabricated by the suction casting and rod-in-tube technologies. The absorption spectrum of Er^{3+}/Yb^{3+} -codoped bulk glass has been measured. From the Judd－Ofelt intensity parameters, the spontaneous emission probability and radiative lifetime τ_{rad} of Er^{3+}:{}^{4}I_{13/2}→{}^{4}I_{15/2} transition for the bulk glass have been calculated. The emission fluorescence spectra and lifetimes around 1.5μm, and subsequent upconversion fluorescence in the range of 500－700nm were measured in fibres and compared with those in bulk glass. The changes in amplified spontaneous emission with fibre length and pumping power was also measured. It was found that the emission spectrum from erbium in fibres is almost twice as broad as the corresponding spectrum in bulk glass when pumped at 980nm.     

Optical and atomic force microscopic study on step bunching in BaB2O4 crystal growth

The formation of macrostep during high-temperature phase of barium meta-borate (α-BaB 2 O 4) single crystal growth has been investigated by both optical in-situ observation system and atomic force microscopy (AFM).The insitu observation results demonstrate that the critical linear size of growing facet exceeding the size that the macrostep generates is significantly anisotropic.The critical linear sizes are around 280 μm and 620 μm for {1010} and {1010} planes,respectively.AFM study illustrates that macrostep train with a height of 150 nm～200 nm is one typical morphological feature of the as-grown crystal surface.The riser of each macrostep consists of several straight and parallel sub-steps,indicating the occurrence of step bunching.Additionally,triangular sub-steps with heights of several nanometers on the treads of the macrosteps are found to be another typical feature of surface morphology,which implies a microscopically competitive bunching of sub-steps between various crystallographic orientations.     

自组惠斯登电桥测电阻中的误差及分析

通过分析惠斯登电桥测电阻的误差,提出改进实验方法提高灵敏度,减小测量误差.     

二分量玻色-爱因斯坦凝聚中的二超流体模型

4He超流体在一定温度下可用二流体模型描述,包括常规流体和超流体两种成分.用这种二流体模型来描述二分量玻色爱因斯坦凝聚时叫做二超流体模型,是从耦合Gross-Pitaevskii方程出发推导得到的.二超流体模型与4He超流体中的二流体模型非常相近.在特定条件下,二超流体中的两个波模行为非常接近4He超流体中二流体模型中...     

一维势垒散射中粒子的概率分布

利用数值计算方法研究了E>U0、0相似文献   

自组装硫化铜微米管的制备及可见光催化性能

以二水合氯化铜为铜源,硫代乙酰胺为硫源,通过共沉淀法成功合成了自组装CuS微米管,该合成方法简单、反应条件温和,是合成纳米材料的一种有效方法。通过扫描电子显微镜（SEM）考察反应时间对产物形貌的影响,并初步研究其形成过程。X射线衍射（XRD）表征产物是CuS。通过改变光催化实验的条件,如催化剂的量、溶液pH值、活性橙的浓度,研究了样品在可见光下对活性橙的光催化性能。     

托卡马克中ICRH天线的优化设计

采用等离子体平板模型和三维天线模型数值模拟了托卡马克中ICRH天线与等离子体的耦合过程, 模拟结果表明在其它实验条件相同的条件下,与反对称电流和馈线端长度短的天线相比,对称电流分布和馈线端长度长的发射天线可获得更有效的功率耦合。     

GISAXS and SAXS studies on the spatial structures of Co nanowire arrays

The spatial structures of magnetic Co nanowire array embedded in anodic aluminium membranes were investigated by grazing incidence small angle X-ray scattering (GISAXS) and conventional small angle X-ray scattering (SAXS) techniques. Compared with SEM observation, the GISAXS and SAXS measurements can get more overall structural information in a large-area scale. In this study, the two-dimensional GISAXS pattern was well reconstructed by using the IsGISAXS program. The results demonstrate that the hexagonal lattice formed by the Co nanowires is distorted (a ≈ 105 nm, b ≈ 95 nm). These Co nanowires are isolated into many structure domains with different orientations with a size of about 2 μm. The SAXS results have also confirmed that the nanopore structures in the AAM can be retained after depositing Co nanowires although the Co nanowires can not completely but only just fill up the nanopores. These results are helpful for understanding the global structure of the Co nanowire array.