Dynamics of Localized Photoexcitations in Condensed Matter Systems

Washington State University, Pullman WA

Investigators

Abstract

******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.