Morphology and microstructure of Ag islands of aggregated atoms on oil surfaces

The morphology evolution of silver islands on silicone oil surfaces is measured and the microstructure of the islands is studied. The deposited Ag atoms diffuse and aggregate on the oil surface and then Ag islands with the width of the order of 102-nm form. After the samples are removed from the vacuum chamber, the immediate measurement shows that the apparent Ag coverage of the total area decays with the magnitude up to (23.0±3.8)% in few minutes. In the following two hours, the samples are kept in the ambient atmosphere and several unexpected results are detected: 1) as the topological structure of the islands evolves, the total area of each island decreases gradually and the maximum decrement measured is around 20%; 2) if an island breaks and becomes two small pieces, the total area decreases obviously; 3) however, if two small islands meet and stick together, a sudden increment of the total area is observed. These phenomena, mirroring the evolution process of the island microstructure, are resulted from both the diffusion of the atoms and the combination of the defects inside the islands.     

Photoluminescence of an Yb3+/Al3+-codoped microstructured optical fibre

An Yb 3+ /Al 3+-codoped microstructured optical fibre is prepared based on photonic crystal fibre technology.The characteristic spectra of preforms and fibres are experimentally investigated.The results show that under a 971 nm excitation,besides the known infrared fluorescence luminescence around 1050 nm,a blue luminescence peak at 486 nm is obtained.Moreover,an unexpected emission peak at 730 nm is also observed.The photoluminescence mechanism of an Yb 3+ /Al 3+-codoped microstructured optical fibre is discussed.The emission peak at 486 nm is attributed to the cooperative upconversion resulting from pairs of Yb 3+ ions,and the emission peak around 730 nm is ascribed to the stimulated Raman scattering because of nonlinear effects of microstructured optical fibre.The Yb 3+ /Al 3+-codoped microstructured optical fibre is promising for varieties of applications from laser printing and optical recording to cancer treatments,such as photodynamic therapy.     

电磁场切向边值关系的讨论

针对目前电动力学和电磁场理论教材中电磁场切向边值关系的推导方法不一及存在的问题,介绍两种推导电磁场切向边值关系的方法并作了相应的讨论.     

二氧化硫脲还原沉析银的电势法研究

本文采用电势法研究二氧化硫脲的银氨溶液以沉析银的反应体系。获知体系温度、ｐＨ值、氨含量对反应速度和银沉析率均有较大的影响。在ＮＨ３和Ａｇ＾＋摩尔比为１８：１时，体系的最佳反应条件是：ｐＨ＝１２．００，温度为５０℃。在此条件下，将二氧化硫脲溶液不断地加入到［Ａｇ（ＮＨ３）２＾＋］溶液中，当反应体系的电势降到－７００ｍＶ（ｖｓ．ＳＣＥ）时，停止加入还原剂，并迅速中止反应，此时银的还原沉析率达９９．９％     

用“最小数原理”证明2~(1/2)是无理数

《中学生数学》2004年3月(上)和2004年8 月(上)分别给出了3~(1/2)是无理数的两种证明,开阔 了同学们的视野．本文用最小数原理证明2~(1/2)是无 理数． “在任何一个自然数集合里．必定存在一个 最小的数．”这就是最小数原理． 下面证明2~(1/2)是无理数． 证明 只须证n·2~(1/2)对任何正整数n都不 是整数． 设S是所有使n·2~(1/2)为整数的正整数n的     

纳米X1-Y2SiO5: Eu3+发光光谱的理论研究

从晶体结构参数和Eu³⁺离子等的物性参数出发，用Faucher的静电模型，计及远程环境影响，且用自洽求解方法确定配位离子的诱导电偶极矩，系统地计算了纳米晶X₁-Y₂SiO₅: Eu³⁺的晶场参数，并延伸此模型用于跃迁强度计算．给出了在C₁对称下与实验相当一致的光谱，且得到可用于其他性质的计算的各态波函数 关键词：     

关于铱(Ir)的晶胞常数a0值的更正

关于铱（Ｉｒ）的晶胞常数ａ０值的更正兰田徐飞岳罗敬良夏都灵Ｉｒ的ａ０值与文献值稍有差别（如３．８５，３．８４和３．８３９等），文献［１］表４和文献［２］表１误用为３．５８，虽然各ｄｎ值未错，但其驰豫量（％）也应修正于后。园括号中为错误数值。Ｉ...     

楔形金薄膜系统中的反常跳跃电导和隧道效应

采用真空蒸镀方法，利用液体衬底在沉积过程中的线性扩散过程，在玻璃表面制备出斜率仅为10^-5的楔形金薄膜逾渗系统，并用四引线方法测量了从该薄膜系统中得到的均匀无序金薄膜的导电特性.实验结果表明：和通常的平整薄膜逾渗系统相比，该薄膜系统呈现更为强烈的跳跃电导和隧道效应. 关键词： 带状薄膜 跳跃电导 隧道效应     

基于离子注入技术的ZnMnO半导体材料的制备及光谱表征

通过离子注入技术制备了ZnMnO半导体材料，研究离子注入剂量与退火对材料光谱性质的影 响.Raman光谱研究发现，575cm^-1处声子模展宽是由高剂量Mn注入引起的缺陷所 致，退火样品528cm^-1振动模来自Mn相关的杂质振动.室温光致发光谱表明，退 火对高剂量注入样品的可见发光带有增强作用. 关键词： ZnMnO 离子注入 Raman光谱 室温光致发光