Low Energy Collisions: Removing the Thermal Averaging

该项目由化学部实验物理化学计划资助，是低能非反应碰撞研究的继续。在这项工作中，俄亥俄州立大学的F.de Lucia博士和E.Herbst博士将探索碰撞的量子特征，以及控制其共振结构的准束缚碰撞复合体的性质。所讨论的低能量对应于低温能量，其旋转能量通常为几厘米-1。重要的细节在量子体系中表现出来，但在室温下进行的实验中被平均出来，在非常低的温度下变得有效。鉴于以前的工作仍然需要热平均化来分析碰撞的影响，本项目所做的研究将消除这种热平均化。其结果是产生了所谓的“碰撞光谱学”，它具有定义明确的、实验上可观察到的共振，并与正常的、基于光子的光谱学和潜在的碰撞参数有直接联系。此外，这项工作还将探索碰撞中形成的瞬时范德华络合物的势能面。该项目所做的工作以及以前的研究工作，对当代物理化学的几个领域具有重要意义，如在天文学、大气科学、化学物理和分析化学中的应用。研究生和本科生以及博士后研究助理参与了这项研究。这些学生和博士后在当代物理化学领域获得技能和宝贵经验，从而为在我国经济的科学/技术部门深造或就业做好准备。

This project, funded by the Experimental Physical Chemistry Program of the Chemistry Division, represents a continuation of studies of non-reactive collisions at low energies. In this work, Drs. F. De Lucia and E. Herbst of the Ohio State University will explore the quantum characteristics of the collisions and the nature of quasi-bound collisional complexes that dominate their resonant structure. The low energies in question correspond to those of low temperatures, with rotational energies of typically a few cm-1. Important details that manifest themselves in the quantum regime, but are averaged out in experiments conducted at room temperature, become effective at very low temperatures. Whereas in the former work thermal averaging was still required to analyze the collisional effects, the research done in this project will remove this thermal averaging. The result is a so-called "collisional spectroscopy" with well-defined, experimentally observable resonances and a direct link both to normal, photon-based spectroscopy and the underlying collision parameters. In addition, the work will probe the potential energy surfaces of the transient van der Waals complexes formed in the collisions.The work done in this project, as well as in the former investigation, has relevance to several areas of contemporary physical chemistry, such as applications to astronomy, atmospheric science, chemical physics, and analytical chemistry. Graduate and undergraduate students, as well as postdoctoral research associates participate in this research. These students and postdoctorals acquire skills and gain valuable experience in a contemporary field of physical chemistry and are thereby prepared for advanced studies or employment in the scientific/technical sectors of our economy.