Laser Studies of Energy Flow in Polyatomic Molecules

在化学学部物理化学项目中，哥伦比亚大学的George W. Flynn教授将继续研究高振动激发分子在微观、量子态分辨水平上的能量传递和猝灭。使用由他开发的二极管激光技术，Flynn教授将在单次碰撞持续时间的时间尺度上研究碰撞反应，这些反应涉及振动和旋转以及平移自由度。要解决的具体问题包括确定导致超碰撞的供体分子的特性，即大量振动能量转移的碰撞；在这些过程中发生的角动量的变化；以及受体分子的质量和其他性质如何影响能量传递。研究对象还包括电子激发分子的猝灭、热原子碰撞和化学反应过程。当代物理化学的突出问题之一是化学反应过程的细节问题。为此，有必要研究被激发到高振动和旋转能量的分子在与其他分子碰撞时的行为。由于反应分子通常遵循几种可能的反应路径之一，导致不同的反应产物，为了建立理论模型，可以控制反应，从而产生最大产量的期望产物，详细了解碰撞伙伴和反应产物之间的振动，旋转和平动能量的转移是可取的，也是必要的。这些研究不仅产生了可以方便地与理论计算相比较的数据，而且还为控制反应过程的机制或力提供了相当明确的证据。此外，获得的许多实验数据将对单分子和双分子化学反应以及光化学的研究和控制具有实际意义。这些过程对于改进微电子设备、开发新的、更高效的激光设备以及提高对大气化学反应和环境重要化学的理解的发展所必需的先进材料和加工技术的发展具有重要意义。

In this project in the Physical Chemistry program of the Chemistry Division, Professor George W. Flynn of Columbia University will continue his investigations on the energy transfer and quenching in highly vibrationally excited molecules at the microscopic, quantum state-resolved level. Using diode laser techniques developed by him, Prof. Flynn will study collisional reactions on a time scale of the duration of a single collision, these involving the vibrational and rotational, as well as translational degrees of freedom. Among the specific problems to be attacked are the determination of the characteristics of the donor molecules that lead to supercollisions, i.e., collisions in which large amounts of vibrational energy are transferred; of the changes in angular momentum which occur in these processes; and how the mass and other properties of the acceptor molecules affect the energy transfer. Also to be investigated are the quenching of electronically excited molecules, hot atom collisions and chemical reaction processes. Among the outstanding problems in contemporary physical chemistry are the details of chemical reaction processes. To this end it is necessary to investigate how molecules excited to high vibrational and rotational energies behave when they undergo collisions with other molecules. Since reacting molecules usually follow one of several possible reactions paths that lead to different reaction products, a detailed understanding of the transfer of vibrational, rotational, and translational energies among the collision partners and the reaction products is desirable, and necessary, in order to develop theoretical models that can lead to the control of reactions so as to yield a desired product with maximum yield. Not only do such studies yield data which can be compared conveniently to theoretical calculations, they also provide rather definite evidence for the mechanism or forces which control reaction processes. In addition, much of the experimental data to be obtained will be of practical interest in the study and control of unimolecular and bimolecular chemical reactions and photochemistry. These processes are of importance in the development of advanced materials and processing techniques necessary for improved microelectronic devices, the development of new, more efficient laser devices, and in the development of an improved understanding of atmospheric chemical reactions and environmentally important chemistry.