Investigation of Quantum Coherence and Correlated Dynamics Using Attosecond Spectroscopy

电子运动是支配我们日常生活的自然现象和实验室现象的基础，例如光合作用、化学过程、电子电路等。作为基本粒子，电子非常灵活，可以在原子、分子和材料内部以阿秒的时间尺度运动，也就是十亿分之一秒的十亿分之一。为了理解对我们很重要的物理、化学和生物过程的功能，能够解析和控制潜在的快速电子运动是有用的。最近设计的阿秒光谱学正好提供了这样一个机会，阿秒持续时间的光脉冲可以用来频闪电子的动力学。该项目支持的研究人员将开发方法来研究电子如何帮助分子内的能量重新分配。沿着这些方向的成功可以为直接控制与光收集和能量储存相关的复杂分子中的化学过程提供机会。因此，拟议中的项目将推动美国在前沿研究领域的科学努力，同时培养具有不同背景的下一代科学家。该项目旨在利用超快光脉冲详细研究量子相干性和相关的电子和核动力学。这些研究将集中在电子之间的相互作用、电子与原子核之间的耦合以及分子与环境之间的相互作用方面，在量子水平上发生了什么。电子叠加演化的自然时间尺度是飞秒到阿秒，因此这些研究将涉及阿秒到飞秒x射线、极紫外光和红外光脉冲的应用。该项目的科学目标是：(1)研究分子激发态的相关衰变动力学；(2)研究相干电荷迁移和退相干机制；(3)实现研究电荷定向反应性的新技术。这些目标将在培养阿秒光谱学领域的研究生和本科生的同时实现。速度图成像和阿秒瞬态吸收技术将在拟议的工作中使用。其深远的目标是在物理学领域与化学、生物学和材料科学领域之间建立桥梁，为控制各种电子驱动过程铺平道路。该项目还将开展外联活动，让本科生和当地社区参与进来，并为代表性不足的群体成员创造先进的研究机会。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。

Electron motion is fundamental to the natural and laboratory phenomena that govern our daily lives, examples being photosynthesis, chemical processes, electronic circuits, etc. Being elementary particles, electrons are extremely agile, and can move inside atoms, molecules and materials on the timescale of attoseconds, which is a billionth of a billionth of a second. To understand the functioning of physical, chemical and biological processes important to us, it is useful to be able to resolve and control the underlying fast electronic motion. Recently devised attosecond spectroscopy provides exactly such an opportunity, where attosecond duration light pulses can be used to strobe the dynamics of electrons. The researchers supported by this project will develop methods to study how electrons help to redistribute energy within molecules. Success along these directions could open up opportunities for direct control of chemical processes in complex molecules relevant for light harvesting and energy storage. The proposed program will therefore advance US scientific efforts in a frontier area of research, while training the next generation of scientists belonging to diverse backgrounds.This project aims for detailed investigation of quantum coherence and correlated electronic and nuclear dynamics using ultrafast light pulses. These studies will focus on what transpires at the quantum level, in terms of interactions between electrons, couplings between electrons and nuclei, and between molecules and the environment. The natural timescale for the evolution of electronic superpositions is in the femtoseconds to attosecond regime, so these investigations will involve the application of attosecond to femtosecond x-ray, extreme ultraviolet, and infrared light pulses. The scientific objectives of the project are: (1) Investigation of correlated decay dynamics of molecular excited states, (2) Study of coherent charge migration and decoherence mechanisms, and (3) Implementation of new techniques to study charge directed reactivity. These objectives will be achieved while training graduate and undergraduate students in the field of attosecond spectroscopy. Velocity map imaging and attosecond transient absorption techniques will be used in the proposed work. The far-reaching objective is to build bridges between the field of physics, and those of chemistry, biology and material sciences, paving the way for control of a variety of electron driven processes. The project will also conduct outreach by involving undergraduates and the local community, and by creating advanced research opportunities for members of under-represented groups.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.