Laser Studies of Equilibrium and Time Dependent Processes at Liquid Interfaces

9313778 Eisenthal哥伦比亚大学的K.B. Eisenthal教授将在化学学部物理化学项目中，利用基于二次谐波和和频产生技术的非线性光学方法研究液体界面的性质和过程。这项工作的目的是在蒸汽/液体、液体/液体和液体/固体界面上获得平衡和时间依赖过程的分子水平描述。平衡过程包括化学平衡，如测量界面酸碱平衡常数的新方法，已知对极性敏感的分子界面上的异构平衡，以及对液体界面上带电分子的研究。超快光化学和光物理事件，如在空气/液体、液体/液体和液体/固体界面上的光异构化，以及界面分子光激发后分子偶极矩的大变化引发的溶剂化动力学和其他现象将被研究。界面是将不同的介质彼此分开的明确划分的几何边界。发生在界面上的化学和物理过程不同于发生在任何介质内的化学和物理过程。一个常见的例子是光束在穿过空气和水之间的边界时发生弯曲。在空气和水这两种介质中沿直线运动时，光束在边界面上弯曲。其他的例子还有液体的蒸发，即单个分子从液体的边界表面移动到蒸气中，以及表面上的化学过程，这些化学过程不同于在散装介质中发生的化学过程。虽然这些和其他常见的界面过程在宏观现象学理论的基础上得到了相当好的理解，但重要的是要知道在分子水平上描述这些过程是如何发生的。本研究项目的目的是研究界面过程，以便在分子之间以及分子与电磁辐射之间的相互作用的基础上理解界面过程。虽然这项研究将关注界面现象的基本化学和物理问题，但它与空气/水、油/水和土壤（硅酸盐）/水界面的主要环境问题有关。＊＊＊

9313778 Eisenthal In this project of the Physical Chemistry Program of the Chemistry Division, Prof. K.B. Eisenthal of Columbia University will investigate the properties of and processes on liquid interfaces using non-linear optical methods based on second harmonic and sum frequency generation techniques. The aim of this work is to obtain a molecular level description of equilibrium and time dependent processes at vapor/liquid, liquid/liquid, and liquid/solid interfaces. The equilibrium processes include chemical equilibria such as a new method for measuring acid-base equilibrium constants at interfaces, isomeric equilibria at interfaces of molecules that are known to be sensitive to polarity, and the investigation of charged molecules at liquid interfaces. Ultrafast photochemical and photophysical events such as photoisomerization at air/ liquid, liquid/liquid, and liquid/solid interfaces as well as the dynamics of solvation initiated by a large change in the molecular dipole moment following photoexcitation of interface molecules and other phenomena will be investigated. %%% Interfaces are the sharply delineated geometric boundaries that separate different media from one another. The chemical and physical processes that occur at interfaces differ from those that take place within either of the media. A common example is the bending of a light beam as it traverses the boundary between air and water. While moving along a straight line path in both media, air and water, the beam is bent at the boundary face. Other examples are the evaporation of a liquid, whereby individual molecules move across the boundary surface from the liquid to the vapor, and chemical processes on surfaces which differ from those that take place in the bulk medium. While these and other common interfacial processes are reasonably well understood on the basis of macroscopic, phenomenological theories, it is important to know on a molecular level of description how these come about. It is the purpose of this research project to investigate interfacial processes in such a way that they can be understood on the basis of interactions between molecules, and between molecules and electromagnetic radiation. Though this research will concern itself with fundamental, basic questions of the chemistry and physics of interfacial phenomena, it has relevance to major environmental issues of air/water, oil/ water, and soil (silicates)/water interfaces. ***