QLC: EAGER: Control of Quantum Dynamics and Catalysis Using Molecular Polaritonics

化学家经常研究光如何与分子相互作用。光谱学是表征分子结构和化学反应的重要工具。近年来，人们对光谱学的一种不同寻常的扭曲越来越感兴趣：如果将装有分子的容器改造成包括两个平行镜子，那么进入容器的光将与样品分子相互作用，并在镜子之间来回反射。如果容器的尺寸恰到好处（几微米，一微米是一米的百万分之一），光和分子的混合就会产生一种新的粒子。这些新的光-物质混合体被称为“极化子”，它们的行为可以通过改变空腔的尺寸或光的波长来控制。在这个由化学部门化学结构动力学和机制（CSDM-A）项目资助的项目中，密歇根大学的Kevin Kubarych教授和他的学生将微腔和先进的基于激光的光谱学结合起来研究极化子的行为。他们感兴趣的是极化子对光照变化的反应，以及极化子分子部分的实际化学反应性是否与正常分子不同，以及它们的反应性是否可以通过改变容器的尺寸来控制。这项研究的一个潜在结果是提高化学反应的效率和经济性，可能包括工业催化过程和与太阳能转换有关的化学反应。分子振动态与腔模之间的强耦合导致了具有分子和光学混合特性的能移态。模式选择耦合提供了外部调节化学结构和能量学的希望，这可以用来操纵弛豫动力学，如激发态电荷转移和基电子态电催化。本研究旨在(1)极大地扩展与微腔耦合的配位配合物的范围，以发展对极化及其弛豫（振动能量弛豫和再分布，以及光谱扩散和相干转移）的基本理解；(2)利用极化调制激发态电荷在分子分叉中转移。利用极化桥接振动控制电子波包的运动；(3)将微腔与电化学相结合，利用薄金层作为腔镜和电化学、电催化电极。参与该项目的学生在超快光谱学、量子动力学、化学反应动力学和电催化方面获得了宝贵的经验。实用电催化技术的改进将大大提高我们在生产有用燃料的同时减少二氧化碳的能力。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Chemists routinely study how light interacts with molecules. Optical spectroscopy is an important tool in the characterization of molecular structure and chemical reactions. In recent years there has been a growing interest in an unusual twist of optical spectroscopy: if the container holding the molecules is modified to include two parallel mirrors, light that enters the container will interact with the sample molecules, and also reflect back and forth between the mirrors. If the dimensions of the container just right (a few microns, where a micron is one millionth of a meter), the mixing of light and molecules creates a new kind of particle. These new light-matter hybrids are called "polaritons," and their behavior can be manipulated by changing the dimensions of the cavity or the wavelength of light. In this project funded by the Chemical Structure Dynamics and Mechanism (CSDM-A) program of the Chemistry Division, Professor Kevin Kubarych of the University of Michigan and his students are combining microcavities and advanced laser-based optical spectroscopy to study the behavior of polaritons. They are interested in how polaritons respond to changes in light exposure, and whether the actual chemical reactivity of the molecular parts of the polaritons is different from normal molecules, and whether their reactivity can be controlled simply by changing the dimensions of the container. A potential outcome of this research is the improved efficiency and economy of chemical reactions, perhaps including industrial catalytic processes and those relevant to solar energy conversion.Vibrational strong coupling between molecular vibrational states and cavity modes leads to energy shifted states that have hybrid molecular and optical character. Mode-selective coupling offers the promise to externally modulate chemical structure and energetics, which can be used to manipulate relaxation dynamics, such as excited state charge transfer and ground electronic state electrocatalysis. This proposal aims to (1) greatly expand the scope of coordination complexes coupled to microcavities to develop fundamental understanding of polaritons and their relaxation (vibrational energy relaxation and redistribution, as well as spectral diffusion and coherence transfer); (2) employ polariton-modulated excited state charge transfer in molecular ?forks? to control the movement of electronic wavepackets with polaritonic bridging vibrations; (3) combine microcavities with electrochemistry using thin gold layers as both cavity mirrors and electrodes for electrochemistry and electrocatalysis. The students involved in this project are gaining invaluable experience in ultrafast spectroscopy, quantum dynamics, chemical reaction dynamics and electrocatalysis. Improvements in practical electrocatalysis stand to dramatically enhance our ability to reduce CO2 while generating useful fuels.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.