Dynamics of Localized Photoexcitations in Condensed Matter Systems

******非技术摘要****本研究将侧重于“局域电子态”的动力学，它在决定许多电子材料的性质方面起着重要作用。这种状态可以极大地改变材料的光学特性以及它们携带电流的能力。这些研究将在材料中进行，其中关键的物理相互作用可以系统地调整。这些系统的研究将使用最先进的超快速光学技术来完成，该技术对电子和结构动力学都很敏感。在这项工作中开发和使用的概念和实验方法将适用于一系列其他光学和电子材料。正在探索的问题在纳米尺度和分子基材料中尤为重要。对这类材料的研究有可能在未来对广泛应用的新技术的发展产生重大影响。该项目的研究将有助于理解对未来技术发展至关重要的关键基本物理过程。学生培训是这项工作的一个组成部分。参与研究的学生将获得使用最先进技术的研究方法和实验技术方面的专业知识，为他们在学术界，工业界或政府的一系列职业生涯提供良好的准备。******技术摘要****这个个人研究项目的重点是局域电子态的动力学，它在决定许多电子材料的性质方面起着重要作用，并且可以显着改变它们的光学特性以及它们的输运特性。研究将在准一维材料中进行，其中关键的物理相互作用，电子-电子和电子-声子相互作用，可以系统地调谐。这些系统的研究将使用飞秒时间分辨技术来完成，这种技术对电子和振动动力学都很敏感。将解决的具体问题包括：1)初始光激发态形成的动力学，(2)激发的电子、振动和结构性质，(3)光诱导缺陷的时间演变，以及(4)电子激发的输运性质。研究中使用的方法包括飞秒光谱学在振动脉冲极限上的时间分辨振动动力学，时间分辨太赫兹光谱学探测极化子动力学，以及时间分辨x射线测量结构和电子动力学。培养研究生是本工作的重要组成部分。参与研究的学生将获得使用最先进技术的研究方法和实验技术方面的专业知识，为他们在学术界，工业界或政府的一系列职业生涯提供良好的准备。

******NON-TECHNICAL ABSTRACT****This research will focus on the dynamics of "localized electronic states," which play an important role in determining the properties of many electronic materials. Such states can dramatically alter the materials' optical characteristics as well as their ability to carry electrical currents. The studies will be carried out in materials in which the key physical interactions can be systematically tuned. Studies of these systems will be accomplished using state-of-the-art ultra-fast optical techniques that are sensitive to both the electronic and structural dynamics. The conceptual and experimental approaches developed and used in this work will be applicable to a range of other optical and electronic materials. The questions being explored can become especially important in nanoscale and molecular-based materials. Research on such materials has the potential for significant future impact on the development of new technologies for a wide range of applications. The studies in this project will contribute to the understanding of key fundamental physical processes that are important for future technological development. Student training is an integral part of the work. Students involved in the research will gain expertise in research methods and experimental techniques using state-of-the-art technology, providing them with excellent preparation for a range of careers in academe, industry, or government.****** TECHNICAL ABSTRACT****This individual investigator project focuses on the dynamics of localized electronic states, which play an important role in determining the properties of many electronic materials, and which can dramatically alter their optical characteristics as well as their transport properties. The studies will be carried out in quasi-one-dimensional materials in which the key physical interactions, the electron-electron and electron-phonon interactions, can be systematically tuned. Studies of these systems will be accomplished using femtosecond time-resolved techniques that are sensitive to both the electronic and vibrational dynamics. Specific issues that will be addressed include: 1) the dynamics of the formation of the initial photoexcited states, (2) the electronic, vibrational, and structural properties of the excitations, (3) the time evolution of the photoinduced defects, and (4) transport properties of the electronic excitations. Methods to be employed in the studies include femtosecond optical spectroscopy in the vibrationally impulsive limit to time-resolve vibrational dynamics, time-resolved terahertz spectroscopy to probe polaron dynamics, and time-resolved x-ray measurements of structural and electronic dynamics. Graduate student training is an integral part of the work. Students involved in the research will gain expertise in research methods and experimental techniques using state-of-the-art technology, providing them with excellent preparation for a range of careers in academe, industry, or government.