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Multi-dimensional electron spectroscopy with photons

光子多维电子能谱

基本信息

批准号：
EP/V007971/1
负责人：
Jan Verlet
金额：
$ 80.02万
依托单位：
Durham University
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2021
资助国家：
英国
起止时间：
2021 至无数据
项目状态：
未结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FV007971%2F1
关键词：
Multi dimensional electron spectroscopy photons

项目摘要

The reaction between an electron and a neutral molecules underpins many branches of science and technology including for example, radiation chemistry and biology, interstellar chemistry, plasma etching in the semiconductor industry, and water remediation. From a basic science perspective, the reaction presents one of the simplest reactions and is a corner stone of physical chemistry. Despite this broad importance, many aspects of this seemingly simple reaction remain unknown and poorly studied. The reactions are deceivingly complex: (i) because of the inherent interplay between the changes in electronic structure (which dictates chemical bonding) and the motion of atoms in molecules, and (ii) because the incoming electron is never actually bound (i.e. energetically, it can always leave). This latter point means that inevitably, the reactions involve unstable species that are very short lived. To probe such transient species requires one to be able to capture the electronic and geometric structure of the entire reaction on the molecular timescale which is on the order of femtoseconds (1 fs = 0.000 000 000 000 001 s). However, there are no experimental methods available to do this directly. The best methods to probe the electron-molecule reaction are based on electron spectroscopic methods. In the past few years, our group has developed analogous methods that use optical excitation rather than electron excitation, with some important benefits, but also some limiting disadvantages. In this proposal, we overcome the limitations and develop methods that can probe the electronic and geometric changes in an electron-molecule reaction in real-time. The new methods are based on the idea that an excess electron can be bound to neutral molecules in an non-perturbing manner and we will exploit these electrons as an intramolecular source of electrons that is well-defined in energy and time. We will then apply these methods to probe the reaction of an electron with nucleobases, which represents a key step in biological radiation damage of DNA and for which the details of product formation and dynamics of excited states in real-time remain uncharted.

电子和中性分子之间的反应支撑了许多科学和技术分支，包括例如辐射化学和生物学、星际化学、半导体工业中的等离子体蚀刻和水治理。从基础科学的角度来看，该反应是最简单的反应之一，是物理化学的基石。尽管这种广泛的重要性，这个看似简单的反应的许多方面仍然未知，研究不足。这些反应复杂得令人难以置信：（1）因为电子结构的变化（决定了化学键）和分子中原子的运动之间存在固有的相互作用;（2）因为进入的电子实际上从来没有被束缚过（也就是说，从能量上讲，它总是可以离开）。这后一点意味着，不可避免地，反应涉及非常短寿命的不稳定物种。为了探测这种瞬态物质，需要能够在飞秒量级（1 fs = 0.000 000 000 000 001 s）的分子时间尺度上捕获整个反应的电子和几何结构。然而，没有实验方法可以直接做到这一点。探测电子-分子反应的最佳方法是基于电子光谱方法。在过去的几年里，我们的团队已经开发出类似的方法，使用光学激发，而不是电子激发，有一些重要的好处，但也有一些限制性的缺点。在这项提案中，我们克服了局限性，并开发了可以实时探测电子分子反应中电子和几何变化的方法。新方法基于这样的想法，即多余的电子可以以非微扰的方式与中性分子结合，我们将利用这些电子作为在能量和时间上明确定义的分子内电子源。然后，我们将应用这些方法来探测电子与核碱基的反应，这是DNA生物辐射损伤的关键步骤，并且实时的产物形成和激发态动力学的细节仍然未知。