固定化发光铂络合物的荧光特性

详细研究了固定化发光铂络合物的荧光特性。根据氧对金属铂络合物发射光的动态猝灭原理及高分子材料的非均一性特征，建立了荧光猝灭动力学模型，并推导出了一个定量描述氧对有机金属铂络合物发射光猝灭作用的通用表达式。该表达式克服了Ｓｔｅｒｎ－Ｖｏｌｍｅｒ方程容易产生负偏差的不足，并能很好地说明固定化发光铂络合物的荧光猝灭机理。     

等离子体破裂期间电流猝灭特征研究

等离子体破裂会对托卡马克装置的安全运行造成严重威胁.等离子体破裂期间电流猝灭速率与电磁负载的大小及逃逸电流平台的形成都密切相关.本文对HL-2A装置等离子体破裂进行了统计分析,统计选用等离子电流的两个衰减区间90%-10%和80%-20%.分析结果表明:HL-2A装置等离子体破裂有四种不同的电流猝灭波形,两个衰减区间最小电流猝灭时间的参数区分别为2.6 ms和2.2 ms,并且不同衰减区间下平均电流猝灭时间统计分布明显不同.     

荧光法研究橙皮苷、淫羊藿苷与溶菌酶的相互作用

应用荧光光谱法研究了生理pH条件下橙皮苷或淫羊藿苷与溶菌酶的相互作用.研究发现,橙皮苷或淫羊藿苷对溶菌酶内源性荧光产生强烈的猝灭作用,测定了不同温度下橙皮苷或淫羊藿苷与溶菌酶反应的猝灭常数,并得出橙皮苷对溶菌酶的荧光猝灭过程为动态猝灭,淫羊藿苷对溶菌酶的荧光产生静态和动态并存的复合猝灭方式.由van't Hoff方程式计算出橙皮苷或淫羊藿苷与溶菌酶反应的热力学参数:焓变△H和熵变△S值分别为20.29 kJ·mol-1,146.28 J·mol-1·K-1和-3.47 kJ·mol-1和81.16 J·mol-1·K-1,表明了橙皮苷与溶菌酶的作用力是以疏水作用为主,而淫羊藿苷与溶菌酶的作用力主要是静电引力,生成自由能变△G均为负值,表明橙皮苷或淫羊藿苷与溶菌酶的作用过程是一个熵增加、Gibbs自由能降低的自发过程.根据F6ster非辐射能量转移理论求出了橙皮苷、淫羊藿苷与溶菌酶色氨酸残基之间的结合距离分别为1.34和1.24 nm.同步荧光研究表明橙皮苷、淫羊藿苷能够使溶菌酶的构象发生变化.     

空穴传输材料对CdSe核壳量子点的荧光影响

用稳态光谱和时间分辨光谱技术研究了空穴传输材料对CdSe/ZnSe与CdSe/ZnS核壳量子点的荧光影响.结果表明,空穴传输材料对量子点有较强的猝灭作用,随空穴传输材料分子浓度的增加,量子点的荧光强度明显地被猝灭,同时量子点的荧光寿命也被减短.两种不同空穴传输分子对CdSc/ZnSe量子点的荧光猝灭明显不同.在与相同空穴传输分子相互作用时,包ZnS壳层的CdSe核壳量子点荧光猝灭效率明显低于包覆ZnSe壳层的CdSe核壳量子点.量子点的荧光猝灭过程可以解释为静态猝灭和动态猝灭过程,其中静态猝灭来源于量子点表面与空穴传输材料问相互作用,而动态猝灭则主要来源于量子点到空穴传输材料的空穴转移过程.实验结果表明空穴传输材料的种类以及核壳量子点的壳层结构都对其荧光猝灭效应起关键作用.     

柠檬酸钠与牛血清白蛋白的相互作用

用荧光光谱法研究了柠檬酸钠与牛血清白蛋白( BSA)的作用机制.实验表明,柠檬酸钠对BSA具有荧光猝灭作用,其猝灭方式为静态猝灭,并求出了猝灭常数、结合常数及结合位点数.     

荧光猝灭法研究苯乙烯氧化物与DNA的相互作用

荧光猝灭法是一种可以研究苯化合物与ＤＮＡ相互作用的动态过程的方法。研究结果表明，苯乙烯氧化物与ＤＮＡ的相互作用与苯乙烯氧化物浓度的关系服从动力学一级方程。     

猝灭式染料激光器理论研究

理论上研究了由准分子激光泵浦的猝灭式染料激光器的猝灭机理，对于一些具体的泵浦情况，通过激光速率方程理论上探讨了激光器的猝灭效果，并且对激光器的一些重要参数进行了一些研究。     

不同粒径金纳米微粒对荧光素钠的猝灭效应研究

采用柠檬酸盐合成法制备了不同粒径的金纳米微粒,用吸收光谱和透射电镜对金纳米微粒进行了表征。研究了不同粒径金纳米微粒与荧光素钠分子的相互作用。发现金纳米微粒对荧光素钠具有荧光猝灭效应,并且其荧光猝灭程度与金纳米微粒的粒径大小有关。随着金纳米微粒粒径的减小,荧光猝灭程度增大。探讨了金纳米微粒对荧光素钠荧光猝灭的机理,表明该荧光猝灭为动态猝灭。     

托卡马克等离子体电流猝灭特征行为分析

对托卡马克装置内壁产生巨大电磁力是等离子体破裂重要和直接的影响, 这会对装置的安全运行造成巨大威胁. 等离子体破裂期间电流猝灭率不仅与真空室内第一壁的负载设计有关, 并且与装置重大部件的设计也相关. 本文选用100%-40%区间统计研究等离子体破裂现象. 分析结果表明: 100%-40%区间统计下HL-2A上最小电流猝灭时间为0.7 ms, 对应的最小面积归一化电流淬灭时间为1.4 ms m-2. 瞬时最大电流猝灭率与平均电流猝灭率的比值大部分都大于1.     

不同区间下电流猝灭特性在等离子体破裂期间的对比研究

托卡马克装置上电磁负载大小值与破裂期间电流猝灭特征有密切的关系.电流猝灭特征包括电流猝灭波形以及电流猝灭率等，它将在一定程度上决定装置的寿命.本文选取100%-40%, 90%-10%, 80%-20%三个区间分析了HL-2A装置上等离子体破裂现象，得到三个不同区间下电流猝灭参数范围.对比分析结果表明：在相同定义下，利用100%-40%和80%-20%区间得到的平均电流猝灭时间以及电流猝灭率分布差异最小.除了80%-20%区间外，100%-40%区间也可作为提供最大线性平均等离子体电流猝灭速率近似的适合区间.     

Correlation between jerky flow and jerky dynamics in a nanoscratch on a metallic glass film

Chaos has been well understood in dynamic system, however, how the chaotic behavior occur in jerky flow in material, is still not clear, and is lack of specific chaotic attractor. Here the jerky evolution of lateral force and the stair-like fluctuation of lateral displacement are observed for Ni62 Nb38(at.%) metallic glass film during nanoscratch process. This jerky flow is investigated by using the largest Lyapunov exponent, Kolmogorov entropy and fractal dimension, and chaotic behavior of lateral force-time and normal displacement-lateral displacement sequences is verified. In addition to time series analysis, it is found that jerk equation can be used to describe the jerky flow of the metallic-glass film during nanoscratch. More importantly, unambiguous chaotic attractor is presented by jerky dynamics using "jerk"-singularities, namely the total change rate of lateral force relative to scratch time. These reveal an inner connection between jerky flow and jerky dynamics in nanoscratch of a metallic-glass film.     

Control of friction at the nanoscale

We propose a new algorithm to control frictional dynamics of a small array of particles towards preassigned values of the average sliding velocity. The control is based on the concepts of non-Lipschitzian dynamics and terminal attractor. Extensive numerical simulations illustrate the robustness, efficiency, and convenience of the algorithm.     

荧光动力学的转移函数理论

为描述弱激发条件下存在能量传递的体系中的荧光动力学特性,引进了响应函数和转移函数,并由此建立了新的描述体系动力学过程的系统表述方法。通过一些实例的讨论,表明新方法是系统研究复杂体系荧光动力学的有效手段。 关键词：     

Escort evolutionary game theory

A family of replicator-like dynamics, called the escort replicator dynamic, is constructed using information-geometric concepts and generalized information divergences from information geometry and statistical thermodynamics. A single-formula Lyapunov function is given that covers the entire class of dynamics, which includes the replicator dynamic and the projection dynamic, as well as several new dynamics. A further class is discussed that allows for more variation, such as variable intensities of selection.     

Quantum necking in stressed metallic nanowires

When a macroscopic metallic wire is subject to tensile stress, it necks down smoothly as it elongates. We show that nanowires with radii comparable to the Fermi wavelength display remarkably different behavior. Using concepts from fluid dynamics, a partial differential equation for nanowire shape evolution is derived from a semiclassical energy functional that includes electron-shell effects. A rich dynamics involving movement and interaction of kinks connecting locally stable radii is found, and a new class of universal equilibrium shapes is predicted.     

Influence of solute mobility on dislocation motion II. Application of the basic model

In many metals containing solute atoms the dynamic strain aging phenomena have been observed at suitable temperatures and strain rates. In this paper a new model of these phenomena based on the assumption that it is the friction stress which is influenced by the dynamic strain aging is developed. The model is used to analyze the flow stress dependence on the dislocation velocity, temperature and solute concentration. The occurence of the plateau stress, the appearance of jerky flow and anomalies in the stress dependence of the strain rate sensitivity are discussed.     

Heterogeneous nucleation and depletion effect in nanowire growth

Recent experiments by Ross and co-workers proved the possibility of a mononuclear regime with heterogeneous nucleation as well as jerky growth in the vapor–liquid–solid (VLS) process for silicon nanowires. In this work, a theoretical model is presented which incorporates the effects of (i) a mononuclear regime with layer by layer growth, (i) heterogeneous nucleation of each new layer at the edge of a Au–Si droplet, (iii) drop of supersaturation after each successful nucleation and respective fast layer growth, (iv) time-dependent nucleation barrier during each new waiting period and (v) correlation between subsequent waiting periods (non-Markovian sequence of waiting periods).     

Laser cooling of molecules via single spontaneous emission

A general scheme for reducing the center-of-mass entropy is proposed. It is based on the repetition of a cycle, composed of three concepts: velocity selection, deceleration and irreversible accumulation. Well-known laser techniques are used to represent these concepts: Raman π-pulse for velocity selection, STIRAP for deceleration, and a single spontaneous emission for irreversible accumulation. No closed pumping cycle nor repeated spontaneous emissions are required, so the scheme is applicable to cool a molecular gas. The quantum dynamics are analytically modelled using the density matrix. It is shown that during the coherent processes the gas is translationally cooled. The internal states serve as an entropy sink, in addition to spontaneous emission. This scheme provides new possibilities to translationally laser-cool molecules for high precision molecular spectroscopy and interferometry. Received 25 June 2002 / Received in final form 28 September 2002 Published online 12 November 2002 RID="a" ID="a"e-mail: ooi@spock.physik.uni-konstanz.de RID="b" ID="b"e-mail: Peter.Marzlin@uni-konstanz.de RID="c" ID="c"e-mail: Juergen.Audretsch@uni-konstanz.de     

力学概念理解和问题解决能力的调查研究

首先介绍Hestences等人开发的MBT(mechanics baseline test)——力学基准测试题目,并且对北京师范大学物理系一年级学生进行了测试,把测试的结果和美国的有关研究结果进行了分析和比较．接着通过一个现实生活中的问题来分析学生解决实际问题的能力,发现教学中存在的问题．最后对我们目前的教学情况进行了评述．