A New Effect in Ultrafast X-ray Scattering

超快X射线散射的新效应

• 批准号: EP/V049240/1
• 负责人: Adam Kirrander
• 金额: $ 78.02万
• 依托单位: University of Edinburgh
• 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: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FV049240%2F1
• 关键词: New; Effect; Ultrafast; ray; Scattering

Light triggers many important chemical reactions. These include photosynthesis (converting sunlight to chemical energy), human vision (detecting photons via light-induced changes in molecules), and new technologies such as photodynamic therapy for cancer, photocatalysis, fluorescent tags for healthcare diagnostics, and photovoltaics. Light-triggered processes in molecules are difficult to study experimentally and involve a complex interplay of concerted changes in molecular structure and rapid rearrangements of the electrons in the molecule. Conical intersections play a decisive role for the outcome of photochemical reactions, analogous to that of a transition state in standard ground-state chemistry. These are regions on photochemical pathways where molecules can transition efficiently between electronic states. Being able to map the path of molecules through conical intersections would open avenues to controlling photochemical reactivity via modification of excited state dynamics. To achieve this we must simultaneously observe the electronic characteristics of the molecule and the corresponding changes in molecular structure. The challenge is compounded by the short timescales involved, on the order of femtoseconds. Notably, there are as many femtoseconds in a second as there are seconds in 30 million years. In contrast, standard techniques for structural determination require long observation times. New facilities known as X-ray Free-Electron Lasers (XFELs) deliver extremely short pulses of intense high-energy x-ray photons, making completely new types of measurements possible. In recent work, we have demonstrated that we can track the changes in molecular structure in excited molecules and, in separate experiments, detect the nearly instantaneous re-arrangement of electrons when molecules absorb light. Exploiting these advances, the proposed project will develop measurements that track the motion of electrons alongside the motion of the nuclei, allowing conical intersections to be identified, and the structure of molecules at conical intersections to be determined. The resulting experimental technique will yield a powerful tool for fundamental research and provide images of electrons and nuclei that can be used to customise photoactive molecules, ultimately contributing to new technologies in catalysis, new cancer treatments, and energy harvesting from sunlight.

光会引发许多重要的化学反应。其中包括光合作用（将阳光转化为化学能）、人类视觉（通过光引起的分子变化检测光子）以及新技术，例如癌症光动力疗法、光催化、用于医疗诊断的荧光标签和光伏。分子中的光触发过程很难通过实验研究，并且涉及分子结构的协同变化和分子中电子的快速重排之间复杂的相互作用。圆锥形交叉点对于光化学反应的结果起着决定性作用，类似于标准基态化学中的过渡态。这些是光化学路径上的区域，分子可以在其中有效地在电子态之间转换。能够通过锥形交叉点绘制分子路径将为通过修改激发态动力学来控制光化学反应性开辟途径。为了实现这一点，我们必须同时观察分子的电子特性和分子结构的相应变化。由于所涉及的时间尺度短（飞秒量级），这一挑战变得更加复杂。值得注意的是，一秒中的飞秒数量与三千万年中的秒数量一样多。相比之下，结构测定的标准技术需要较长的观察时间。称为 X 射线自由电子激光器 (XFEL) 的新设施可提供极短的强高能 X 射线光子脉冲，使全新类型的测量成为可能。在最近的工作中，我们证明我们可以跟踪受激分子中分子结构的变化，并在单独的实验中检测分子吸收光时几乎瞬时的电子重新排列。利用这些进步，拟议的项目将开发跟踪电子运动和原子核运动的测量方法，从而识别圆锥形交叉点，并确定圆锥形交叉点处的分子结构。由此产生的实验技术将为基础研究提供强大的工具，并提供可用于定制光活性分子的电子和原子核图像，最终有助于催化新技术、新的癌症治疗和从阳光中收集能量。

项目成果

Heavy Rydberg and ion-pair states: chemistry, spectroscopy and theory

重里德伯态和离子对态：化学、光谱学和理论

• DOI: http://dx.10.1080/0144235x.2022.2077024
• 发表时间: 2022
• 期刊: International Reviews in Physical Chemistry
• 影响因子: 6.1
• 作者: Donovan R

Highlights from Faraday Discussion 228: time resolved imaging of photo-induced dynamics.

法拉第讨论 228 的要点：光致动力学的时间分辨成像。

• DOI: http://dx.10.1039/d1cc90220b
• 发表时间: 2021
• 期刊: Chemical communications (Cambridge, England)
• 作者: Dixit G

Preface.

前言。

• DOI: http://dx.10.1039/d1fd90034j
• 发表时间: 2021
• 期刊: Faraday discussions
• 影响因子: 3.4
• 作者: Dixit G

Brighter, faster, stronger: ultrafast scattering of free molecules

更亮、更快、更强：自由分子的超快散射

• DOI: http://dx.10.1080/23746149.2022.2126796
• 发表时间: 2022
• 期刊: X
• 作者: Odate A

Multichannel photodissociation dynamics in CS2 studied by ultrafast electron diffraction.

通过超快电子衍射研究 CS2 中的多通道光解离动力学。

• DOI: http://dx.10.1039/d2cp01268e
• 发表时间: 2022
• 期刊: PCCP
• 作者: Razmus WO