Energy Exchange between Nuclei and Electrons: A Fundamental Chemical Question Addressed by Pure Electronic Rydberg Spectroscopy

麻省理工学院的罗伯特·菲尔德得到了实验物理化学计划的支持，以开发实验方法，理论模型和直观的概念，通过这些概念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。 实验将在高度激发的电子状态下对小的气相分子进行，目标是在所有激发能量下和凝聚相中对其电子核耦合的机制和强度产生基本的见解，这些机制和强度与较大的分子密切相关。多路复用时域太赫兹光谱将与多个纳秒染料激光激发结合使用，在多激光方案中，这将使得能够在超声分子束条件下探测分子里德伯发射状态。 光谱和动力学复杂性增加的分子的纯电子光谱研究（CaF、CaCl和二氧化氮）有望展示纳秒/飞秒组合方法的能力，以最少的光谱检测工作表征重要的电子-核能交换机制，包括它们对分子几何形状的依赖性。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分子中的能量耦合和流动产生重要影响。 该项目将使学生能够进行有效的研究培训。 此外，菲尔德还写了一本扩展和重新聚焦的分子光谱学教科书，预计对研究和教育应用有价值。

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. Multiplexed time-domain terahertz 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/femtosecond 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.