U.S.-UK Cooperative Research: Accurate Semiclassical Methods for Redistribution of Polarized Radiation

该奖项将支持密苏里大学罗拉分校的Ronald Bieniek博士与两位英国科学家（牛津大学克拉伦登实验室的Keith Burnett博士和牛津大学理论化学系的Mark Child博士）在理论物理方面的合作研究。本研究旨在建立精确的半经典模型和方法来描述和分析极化辐射的碰撞和半碰撞重分布。当偏振光在原子/分子紧密的完全或半碰撞中被吸收时，碎片分离后会发出荧光。光中剩余的偏振度，作为激光失谐的函数，包含了许多关于分子间势和从分子域到原子域的基本转变的信息。如果有准确的、易于处理的理论工具，研究人员可以利用这些工具将现象形象化，并描述潜在的物理现象，那么对有关性质的实验信息的分析就会大大便利。半经典技术，以经典的方式处理某些方面，而以量子力学的方式处理其他方面，可以提供相当大的洞察力。然而，目前的半经典的再分配方法在许多方面是不令人满意的。本项目旨在通过改进流行的锁定/解耦模型，并开发新技术来处理激励事件之间的相位干涉效应，轨道旋转的科里奥利制动以及原子与分子之间的边界的变化耦合角动量。参与的英国合作者处于再分配研究的前沿，美国研究者Bieniek博士将从进行这次长期研究访问的机会中受益匪浅。

This award will support collaborative research in theoretical physics between Dr. Ronald Bieniek, University of Missouri at Rolla, and two British scientists: Dr. Keith Burnett, Clarendon Laboratory, Oxford University and Dr. Mark Child, Theoretical Chemistry Department, Oxford University. The proposed study is aimed at developing accurate semiclassical models and methods of describing and analyzing collisional and half-collisional redistribution of polarized radiation. When polarized light is absorbed during a close atomic/molec- ular full- or half-collision, the fragments will flouresce light after they separate. The degree of polarization remaining in the light, as a function of laser detuning, contains much information about intermolecular potentials and the fundamental transition from molecular to atomic domains. The analysis of experimental information about properties is greatly facilitated if accurate and tractable theoretical tools are available with which investigators can visualize the phenomena and describe the underlying physics. Semiclassi- cal techniques, which treat some aspects in a classical way and others in a quantum mechanical manner, can offer considerable insight. However, current semiclassical methods for redistribution are, in many ways, unsatisfactory. This project is designed to improve this situation by enhancing the popular locking/decoupling model, and developing new techniques to deal with phase interference effects between excitation events, Coriolis braking of orbital rotation, and the vagaries of the boundary between the atomic and the molecular coupling of angular momenta. The British collabora- tors involved are at the forefront of redistribution research and the US investigator Dr. Bieniek will benefit greatly from the opportunity to carry out this long term research visit.