Observations and Applications of Dissociative Electron Transfer Reactions in Selected Molecular Systems

解离电子转移（DET）是化学、生物和环境系统中许多分子反应的基础。在过去的十年中，申请人（Lu）专注于各种分子体系中弱束缚电子的DET反应的研究，并发现了它们在各种主题中的重要作用，从环境重要的卤化分子反应和电离辐射诱导的DNA损伤到抗癌药物的激活。这个更新提案描述了一个连续的程序来研究弱束缚电子在选定的具有环境和生物学意义的分子系统中的DET反应。该项目的目的是获得电离辐射下水溶液中卤化分子DET反应的实时观测结果，并探索其环境和生物医学应用。然而，该提案将只关注物理科学方面的研究挑战。

Dissociative electron transfer (DET) underlies many molecular reactions in chemical, biological and environmental systems. Over the past decade, the applicant (Lu) has focused on research on DET reactions of weakly-bound electrons in various molecular systems, and discovered their crucial roles in a variety of topics, ranging from the reactions of environmentally important halogenated molecules and ionizing-radiation induced DNA damage to the activation of anticancer drugs. This renewal proposal describes a continuous program to study DET reactions of weakly-bound electrons in selected molecular systems of environmental and biological significance. The objectives of this program are to obtain real-time observations of the DET reactions of halogenated molecules in aqueous solutions under ionizing radiation and to explore their environmental and biomedical applications. This proposal however will only focus on research challenges in the physical sciences. Real-time observations of molecular reactions are important to understand many processes and outcomes in diverse fields from chemistry and biology, to environmental and medical sciences. The monitoring of the reactions on the molecular scale can lead to the identification of molecular pathways controlling the reactions; once the pathways are identified, the reactions can be predicted, modified and controlled. Femtosecond time-resolved laser spectroscopy (fs-TRLS) is a tremendously powerful technique for real-time observations of molecular reactions. The proposed research will combine fs-TRLS with DNA damage assays to study the biological effects. Specifically, we will demonstrate how the proposed DET reactions of halogenated molecules with weakly-bound electrons produced by ionizing radiation occur in real time, and determine their reaction efficiencies. This program is built on an innovative research strategy and the Applicant's recent advances on a novel reaction mechanism in molecular systems. It is at the cutting edge of environmental physics and chemistry, biophysics, biochemistry, photophysics, femtochemistry and femtobiology, and is grounded in solid previous studies. The results are expected to provide a deep understanding of the reaction mechanisms of halogenated molecules and their effects on important environmental and biological processes such as ozone depletion and DNA damage. This project may also ultimately lead to important applications in environmental protection and remediation, and human health.