Pure Electronic Rydberg Spectroscopy: The Use of Chirped-Pulse Millimeter-Wave and Time-Domain TeraHertz Spectroscopies to Reveal the Mechanisms of Electron<-->Cation

麻省理工学院的Robert Field在实验物理化学项目的支持下，开发了实验方法、理论模型和直观概念，通过这些方法，可以表征电子和分子阳离子之间的能量和角动量交换机制。实验将在高度激发态的小气相分子上进行，目的是对其电子-核耦合的机制和强度产生基本的见解，这些机制和强度与所有激发态和凝聚态的大分子密切相关。啁啾脉冲毫米波光谱将与多个纳秒染料激光激发结合使用，在多个激光方案中，将能够探测超音速分子束条件下的分子里德伯发射态。对光谱和动力学复杂性不断增加的分子（CaF、CaCl和二氧化氮）的纯电子能谱研究有望证明纳秒可调谐激光/啁啾脉冲毫米波组合方法的力量，以最少的光谱探测工作来表征重要的电子-核能交换机制，包括它们对分子几何形状的依赖。电子传递、电子能量的收集和处理以及化学键的形成和断裂都涉及到分子中电子和原子核之间的能量交换。这项工作的研究成果有可能对理解能量耦合和分子流动产生重要影响。这个项目将使学生的研究训练有效。此外，菲尔德还编写了一本扩展和重新聚焦分子光谱学的教科书，预计对研究和教育应用具有价值。

Robert Field of MIT is supported by the Experimental Physical Chemistry Program to develop experimental methods, theoretical models, and intuitive concepts by which the mechanisms for exchange of energy and angular momentum between an electron and a molecular cation may be characterized. Experiments will be carried out on small, gas phase molecules in highly excited electronic states with the goal of generating fundamental insights into the mechanisms and strength of its electron - nuclear coupling that are germane to larger molecules, at all excitation energies, and in condensed phases. Chirped-pulse millimeter-wave spectroscopy will be used in combination with multiple nanosecond dye laser excitation, in multi-laser schemes that will enable the probing of molecular Rydberg launch states under supersonic molecular beam conditions. Pure electronic spectroscopy studies of molecules of increasing spectroscopic and dynamical complexity (CaF, CaCl, and nitrogen dioxide) are expected to demonstrate the power of the combined nanosecond tunable laser/Chirped-pulse millimeter-wave approaches to characterize, with a minimum of spectroscopic detective work, important electron - nuclear energy exchange mechanisms including their dependence on molecular geometries.Electron transport, electronic energy harvesting and disposal, and the making and breaking of chemical bonds all involve the exchange of energy between electrons and nuclei in molecules. Research outcomes from this effort have the potential to lead to important impacts in the understanding of energy couplings and flow in molecules. This project will enable effective research training of students. As well, Field has written an expanded and refocused textbook in molecular spectroscopy that is expected to be valuable for research and education applications.