隧穿谱的研究进展

隧穿谱适宜于研究表面和界面的物理化学性质．它具有灵敏度高、谱范围宽和不受光学跃迁那样的选择定则限制等优点．本文介绍了隧穿谱的测量原理及其在探测分子的振动跃迁、电子跃迁，测量超导能隙和研究生物辐射损伤等方面的应用．对扫描隧穿显微镜（ＳＴＭ）的针尖－平面电极构成的隧道结构和金属－氧化物－金属平面型隧道结构作了比较，分析了它们用于测量隧穿谱时的优缺点，ＳＴＭ将促进隧穿谱研究的进一步发展．     

在扫描隧穿显微镜实验中开展研究性学习的教学与实践

介绍了在扫描隧穿显微镜实验中开展研究性学习的教学与实践．举例介绍了具体做法及取得的教学效果。     

铜箔上生长的六角氮化硼薄膜的扫描隧道显微镜研究

利用扫描隧道显微镜研究了采用化学气相沉积法在铜箔表面生长出的高质量的六角氮化硼薄膜. 大范围的扫描隧道显微镜图像显示出该薄膜具有原子级平整的表面, 而扫描隧道谱则显示, 扫描隧道显微镜图像反映出的是该薄膜样品的隧穿势垒空间分布. 极低偏压的扫描隧道显微镜图像呈现了氮化硼薄膜表面的六角蜂窝周期性原子排列, 而高偏压的扫描隧道显微镜图像则呈现出无序和有序排列区域共存的电子调制图案. 该调制图案并非源于氮化硼薄膜和铜箔衬底的面内晶格失配, 而极有可能来源于两者界面处的氢、硼和/或氮原子在铜箔表面的吸附所导致的隧穿势垒的局域空间分布.     

量子隧穿中的等效势垒

本文给出等效垫垒的概念及性质，利用等效势垒的性质可以使量子遂穿中的有关问题更容易解决。     

更新型的扫描隧道显微镜

20世纪重要的发明之一就是扫描隧道显微镜 ,简称为STM .它能对金属及其他导电表面给出原子水平上的形态结构图 .最近美国科罗拉多矿学院的P .Sutter教授对STM设计了一种新的技术 ,称之为“能量过滤STM” .这项技术类似于在普通显微镜上加一个“颜色滤波片” ,使我们能方便地在摄影时分辨出想要寻找的特征 .同时 ,“能量过滤STM”也使我们能容易地区分出一些具有相似化学性质的原子 ,这类原子用其他手段常常很难分辨 .“能量过滤STM”还能确认在表面上的各种类别的化学键 .一般的STM是使用一个金属的探针 ,它对导电表面上的高能电子…     

用扫描隧道显微术实现室温下的单电子隧穿效应

单电子隧穿效应通常只能在低温下实现。最近，采用扫描隧道显微术在纳米尺度的范围内实现了室温单电子隧穿，清晰地观察到了库仑阻塞现象和库仑阶梯特性。这是单电子隧穿研究中的重大进展，将在简要叙术单电子隧穿物理过程的基础上予以介绍。     

扫描隧道显微镜图象的重构

扫描隧道显微镜(STM)图象的解析，是STM应用的关键问题之一，STM的原始图象不能适应各种需要，而采用各种方法重构后，可以适应不同的应用。本文介绍了6种不同的重构方法。     

偏压在隧道效应中的作用

从隧道扫描势垒模型出发。用量子力学导出隧道电流与针尖间的偏压、间距及它们的逸出功之间的关系,并从能带模型的角度导出样品与针尖的间距不变时,隧道电流与偏压成正比关系．指出偏压的作用主要是提高针尖上电子的能量,使针尖上的电子比样品上的电子更容易穿过势垒,从而形成隧道电流．     

分子磁体中的量子隧穿及宏观量子效应

文章介绍了分子磁体中的量子隧穿和宏观量子效应理论和实验研究的新进展．分子磁体既有宏观磁体特性也呈现纯量子行为，例如磁化矢量的量子隧穿．文章作者解释了如何通过量子隧穿实现宏观量子相干(即薛定谔猫态的相干叠加)和量子态位相干涉．对隧穿率计算的瞬子方法，特别是有限温度隧穿理论及其在分子磁体量子隧穿中的应用也做了简要的阐述．     

Adsorption of L-Alanine on Cu（111） Studied by Scanning Tunnelling Microscopy

The adsorption of L-alanine on Cu（111） surface is studied by means of scanning tunnelling microscopy under ultra-high vacuum conditions. The results show that the adsorbates are chemisorbed on the surface, and can form a two-dimensional gas phase, chain phase and solid phase, depending on deposition rate and amount. The adsorbed molecules can be imaged as individual protrusions and parallel chains in gas and chain phases respectively. It is also found that alanine can form （2 × 2） superstructure on Cu（111） and copper step facet to （110） directions in solid phase. On the basis of our scanning tunnelling microscopic images, a model is proposed for the Cu（111）（2 ×2）-alanine superstructure. In the model, we point out the close link between （110）-direction hydrogen bond chains with the same direction copper step faceting.     

From Schwarzschild to Kerr due to Black Hole Quantum Tunnelling

Hawking radiation can be viewed as a process of quantum tunnelling near black hole horizon. When a particle with angular momentum tunnels across the event horizon of Schwarzschild black hole, the black hole will change into a Kerr black hole. The emission rate of the massless particles with angular momentum is calculated, and the result is consistent with an underlying unitary theory.     

From Femtochemistry to 4D Microscopy

To celebrate the 10th anniversary of the Nobel Prize for Femtochemistry,the field is overviewed with several classic examples and the new extension to Femtobiology. The revolutionary breakthrough in 4D electron microscopy is briefly introduced here and a new age to structural dynamics is rising on the horizon,an exciting time and a great opportunity for China and for the world.     

Two-Color Two-Photon Fluorescence Laser Scanning Microscopy

We present the first realization of a Two-Color Two-Photon Laser-Scanning Microscope (2c2pLSM) and UV fluorescence images of cells acquired with this technique. Fluorescence is induced by two-color two-photon absorption using the fundamental and the second harmonic of a Ti:Sa femtosecond laser. Simultaneous absorption of an 800 nm photon and a 400 nm photon energetically corresponds to one-photon absorption at 266 nm. This technique for Laser-Scanning Microscopy extends the excitation wavelength range of a Ti:Sa powered fluorescence microscope to the UV. In addition to the known advantages of multi-photon microscopy like intrinsic 3D resolution, reduced photo damage and high penetration depth 2c2pLSM offers the possibility of using standard high numeric aperture objectives for UV fluorescence imaging. The effective excitation wavelength of 266 nm corresponds especially well to the excitation spectrum of tryptophan. Hence, it is an ideal tool for label free fluorescence studies and imaging of intrinsic protein fluorescence which originates mainly from tryptophan. Thus a very sensitive natural lifetime probe can be used for monitoring protein reactions or changes in conformation. First measurements of living MIN-6 cells reveal differences between the UV fluorescence lifetimes of the nucleus and cytoplasm. The significance of this method was further demonstrated by monitoring the binding of biotin to avidin.     

近场光学扫描显微镜图像的噪音处理

在近场光学扫描显微镜及其它一些以扫描方式成像的系统中,由于图像是逐行扫描而成,因此扫描图像行与行之间存在较大的噪音.针对这种情况及相应的含噪近场光学图像模型,并结合对近场光学扫描图像及其行噪音特点的分析,提出了根据图像行间相关性寻找行噪音补偿因子.同时考虑图像背景波动性选择噪音补偿因子,以此进行行噪音的消除.在此基础上,利用小波变换进一步处理,消除随机起伏噪音.实验结果表明,本方法可以快速有效地去除扫描图像行噪音,且适用于各类扫描图像的处理.     

扫描力显微镜研究进展

在讨论扫描力显微镜基本原理基础上，详细介绍了近期ＳＦＭ成像模式和技术的发展以及它们在表面研究中的应用。     

偏振共焦扫描激光显微镜的成像特性研究

讨论了共焦扫描激光显微镜的纵向分辩率和信噪比对三维成像能力的影响, 给出了纵向分辨率极限的判据, 提出了旨在提高信噪比进而获取强表面反射或弱散射物体以及偏振物体的显微结构图像的偏振共焦扫描激光显微镜     

Archaeological Ceramics Studied by Scanning Electron Microscopy

The use of scanning electron microscopy combined with energy dispersive X-ray fluorescence analysis in studies of archaeological pottery is discussed. The methods are described and results of their application to studies of Precolumbian glossy black pottery from northern Peru are reported in some detail.