Dynamics of Excited Electronic States in DNA

在这个由化学系化学结构、动力学和机制项目资助的项目中，蒙大拿州立大学的伯尔尼科勒教授将与他的研究生和本科生一起，对紫外光吸收在单链和双链DNA中产生的激发电子态进行自下而上的研究。这些激发态是生物体中破坏性光化学反应的来源。广泛可调谐的飞秒激光器将用于测量各种DNA模型系统的瞬态电子和振动光谱，以确定电子能量的演化如何通过碱基堆积和碱基配对进行修改。实验将在修饰的寡核苷酸上进行，以了解结构无序对非辐射衰变途径的影响。电荷转移激发的特点是时间分辨的振动光谱的DNA模型系统，含有修改和天然的核碱基，并通过比较实验结果与电子结构计算将由合作者进行。通过探测对氢键敏感的振动模式，将有针对性地理解双链DNA中质子耦合电子转移的机理。除了其生物学意义外，DNA是研究复杂分子结构中光沉积的能量如何随时间演变和耗散的重要模型系统。通过了解DNA双螺旋对紫外光的反应与更小的DNA构建块的反应如何不同，这项研究将有助于预测和定制包括纳米材料在内的其他光活性成分复杂组件的光学特性。科勒教授还将参加一个试点项目，为蒙大拿州农村学校的儿童提供高质量的科学教育。将开发互动科学工具包，并邮寄给蒙大拿州服务不足地区的教师。我们的目标是通过沉浸式的实践活动为教师和学生提供更丰富的学习体验，并与蒙大拿州的科学家榜样建立关系。通过交互式视频会议。

In this project, funded by the Chemical Structure, Dynamics, and Mechanisms Program of the Division of Chemistry, Professor Bern Kohler of Montana State University, together with his graduate and undergraduate students, will conduct a bottom-up investigation of excited electronic states created in single- and double-stranded DNA by the absorption of UV light. These excited states are the source of damaging photochemical reactions in living organisms. Widely tunable femtosecond lasers will be used to measure transient electronic and vibrational spectra of various DNA model systems in order to determine how the evolution of electronic energy is modified by base stacking and base pairing. Experiments will be performed on modified oligonucleotides in order to understand the effects of structural disorder on nonradiative decay pathways. Charge transfer excitations will be characterized by time-resolved vibrational spectra of DNA model systems containing modified and natural nucleobases and by comparison of experimental results with electronic structure calculations to be performed by collaborators. By probing vibrational modes that are sensitive to hydrogen bonding, mechanistic understanding of proton-coupled electron transfer in double-stranded DNA will be targeted.Apart from its biological significance, DNA is an important model system for studying how energy deposited by light in a complex molecular structure evolves in time and is dissipated. By understanding how the response of the DNA double helix to UV light differs from the response of much smaller DNA building blocks, the research will benefit efforts that seek to predict and tailor the optical properties of other complex assemblies of light-active components, including nanomaterials. Prof. Kohler will also participate in a pilot project to deliver top-quality science education to rural Montana school children. Interactive science kits will be developed and mailed to select Montana teachers in underserved areas of the state. The goal is to give teachers and their students a richer learning experience through immersive, hands-on activities and to foster relationships with scientist role models from Montana?s land grant university through interactive videoconferencing.