Optical Excitations and Applications in Novel Organic Macromolecular Aggregates

在创造能量收集和非线性光学器件的新材料的过程中，一个重要的步骤是理解基于尺寸、几何（循环、二维）和分子内相互作用的结构-功能关系。该提案旨在开发新型有机多功能材料，并使用超快速相干光谱来探测这些材料中的能量迁移，非线性光学和量子干涉现象。PI将对几个新的聚合系统进行调查。具体而言，我们将利用飞秒时间分辨荧光上转换、瞬态吸收、瞬态光栅、三脉冲光子回波峰移实验等飞秒光谱方法与稳态光谱相结合，深入研究各种新型大分子聚集结构。这些结构包括对称性破坏的树状大分子，新的二维大分子结构，巨大的环状大分子噻吩聚集体，以及一种新的卟啉聚集体。PI将根据最近的理论方法进行广泛的建模，这些理论方法描述了激子迁移、自捕获和聚合系统之间激发能转移的细节。该提案的更广泛影响是针对科学教育计划的科学教育活动，这些活动在鼓励不同背景的年轻科学家以及妇女的参与方面取得了成功。PI将继续带领年轻科学家进入材料科学领域，并通过参加夏季充实和指导计划（作为校园和国家组织的一部分）来激发科学事业。与安娜堡和底特律公立高中的持续互动将在PI实验室的夏季研究机会中进行。

TECHNICAL SUMMARYAn important step in the process of creating new materials for energy harvesting and nonlinear optical devices is in the understanding of the structure-function relationships based on size, geometry (cyclic, 2-dimensional), and intramolecular interactions. This proposal is directed at the development of novel organic multifunctional materials and the use of ultra-fast coherent spectroscopy to probe energy migration, nonlinear optical, and quantum interference phenomena in these materials. The PI will carry out Investigations of several novel aggregated systems will be performed. Specifically, using a combination of femtosecond spectroscopic methods such as femtosecond time-resolved fluorescence upconversion, transient absorption, transient grating, three pulse photon echo peak shift experiments complemented with those of steady state spectroscopy we will deeply investigate a variety of novel macromolecular aggregated architectures. These architectures include dendrimers with broken symmetry, new two-dimensional macromolecular structures, giant cyclic macromolecular thiophene aggregates, as well as a novel porphyrin aggregate. The PI will perform extensive modeling based on recent theoretical approaches describing exciton migration, self-trapping and the details of the excitation energy transfer between aggregated systems. NON-TECHNICAL SUMMARYThe broader impact of this proposal is directed to the PI's science education activities which have been successful in encouraging young scientists of diverse backgrounds as well as the participation of women. The PI will continue to bring young scientists into the field of material science and inspire careers in science with participation in summer enrichment and mentorship programs as part of on campus and national organizations. Continued interactions with Ann Arbor and Detroit public high schools will be carried out in summer research opportunities in the PI's laboratory.