Time-Resolved Photoelectron Spectroscopy: Probing Nonadiabatic Dynamics in Polyatomic Molecules

在这个由化学系化学结构、动力学和机制项目支持的项目中，加州理工学院的Vincent McKoy教授和他的研究小组将开发用于模拟飞秒时间分辨光电子能谱（TR-PES）数据的量子力学方法。TRPES是一种可以揭示分子内部动力学的技术，包括分子被光激发时原子的运动和电子结构的变化。这项研究的重点将是非绝热动力学，特别是锥形交叉负责内部转换和光解。由于光电离振幅迅速变化的锥形交叉点附近的核坐标，计算跟踪这种几何依赖性是必不可少的提取波包动力学从测量的能量和角度分辨的光电子分布。即将进行的研究直接关系到对多原子分子动力学的理解，包括DNA核碱基的光稳定性和光敏蛋白质发挥作用的机制等重要问题。因此，除了有助于相关实验的设计和解释外，这项研究还具有广泛的生物物理和生物医学意义。从长远来看，光子与生物分子相互作用的详细知识可能有助于开发，例如，仿生光敏系统或遗传毒性光疗癌症。此外，通过为培训理论分子光电子能谱的年轻研究人员提供背景，该研究项目解决了一个关键的需求，因为全世界很少有理论家支持活跃在这一领域的许多实验小组。这项研究将在与美国研究小组的长期、富有成效和互利的合作中进行，日本、加拿大和巴西。

In this project supported by the Chemical Structure, Dynamics, and Mechanisms Program of the Division of Chemistry, Professor Vincent McKoy and his research group at the California Institute of Technology will develop quantum mechanical methods for simulating femtosecond time-resolved photoelectron spectroscopy (TR-PES) data. TRPES is a technique that can reveal the internal dynamics of a molecule, including the motion of atoms and changes in electronic structure when the molecule is excited by light. The focus of this research will be on non-adiabatic dynamics, especially conical intersections responsible for internal conversion and photodissociation. Because photoionization amplitudes vary rapidly with the nuclear coordinates near conical intersections, calculations that track this geometry dependence are essential to extract the wave-packet dynamics from measured energy- and angle-resolved photoelectron distributions. The research to be undertaken bears directly on understanding the dynamics in polyatomic molecules, including such important issues as the photostability of the DNA nucleobases and the mechanisms by which light-sensitive proteins function. Besides aiding in the design and interpretation of related experiments, therefore, this research also has wide biophysical and biomedical implications. Detailed knowledge of photon interactions with biomolecules may in the long run assist in developing, for example, biomimetic photosensitive systems or genotoxic phototherapies for cancer. By providing a context for training younger researchers in theoretical molecular photoelectron spectroscopy, moreover, this research project addresses a critical need, since there are very few theorists worldwide to support the many experimental groups active in this field. The research will be carried out within longstanding, productive, and mutually beneficial collaborations with research groups in the U.S., Japan, Canada, and Brazil.