Ion-radical reactions relevant to the interstellar medium and outer atmosphere, under cold controlled collisions

该项目福尔斯EPSRC物理科学主题，与分析科学，化学反应动力学和机制以及冷原子和分子研究领域特别相关。该项目的主要目标是通过结合塞曼减速器和低温离子阱来研究极端条件下的离子自由基反应。离子和自由基是高度反应性的物质，因此它们的反应通常非常具有挑战性，难以精确研究。事实上，其他竞争反应通道的存在通常使靶反应的研究复杂化（或在某些情况下，甚至阻止）。通过克服这一挑战，我们将能够获得与星际介质或外层大气相关的许多离子自由基反应的反应速率，这些反应速率尚未通过实验测量。这些数据对于验证理论家在这种介质中的反应模型具有极大的意义。为了实现这一目标，我将开发和设计一种新的实验装置来研究气相中的离子自由基反应。我们已经有了一个由塞曼减速器和磁性导向器提供的冷的和受控的自由基物种的来源。这种冷自由基的来源不仅会选择感兴趣的自由基种类的量子态，而且还会调整和过滤它们的速度。我们将联合收割机和低温离子阱结合在一起。该低温离子阱将被低温冷却到低于10 K，以减少黑体辐射，从而降低分子离子的内部温度。我正在建造一个新的低温离子阱。该设备还配备了振动隔离系统和成像检测方法，将与质谱检测能力相结合。为了处理离子阱的更有效、紧凑的设计，已经开发了新的光学成像系统。由此产生的仪器将使我们能够研究离子和自由基之间的反应，对反应参数进行前所未有的控制。我们将能够以异常的灵敏度研究这些反应系统，因为我们可以监测单个离子的反应。没有其他仪器将低温离子捕获环境与光学访问、质谱检测能力和冷自由基反应物源相结合。

This project falls within the EPSRC Physical Sciences theme, with particular relevance to the Analytical Science, Chemical Reaction Dynamics and Mechanisms and Cold Atoms and Molecules research areas. The primary objective of this project is to study ion-radical reactions under extreme conditions, by combining a Zeeman decelerator and a cryogenic ion-trap. Ions and radicals are highly reactive species, therefore their reactions are frequently really challenging to study precisely. Indeed, the presence of other competing reaction channels typically complicates (or, in some cases, even prevents) the study of target reactions. By overcoming this challenge, we will be able to obtain reaction rates for many ion-radical reactions relevant to interstellar medium or outer atmosphere, that are yet to be experimentally measured. These data are of great interest for validating theoreticians' models of reactions in such media. In order to achieve this objectives, I will develop and characterise a novel experimental set-up to study ion-radical reactions in gas phase. We already have a source of cold and controlled radical species provided by a Zeeman decelerator and a magnetic guide. This source of cold radicals will not only quantum-state select radical species of interest, but also tune and filter their velocities. We will combine a cryogenic ion-trap to the source of cold radicals. This cryogenic ion trap will be cryogenically cooled to less than 10 K to reduce the black body radiation and therefore to lower the internal temperature of molecular ions. I am in the process of constructing this new cryogenic ion trap. The device is also equipped with a vibration-isolation system and an imaging detection methodwill be combined with mass spectroscopy detection capabilities. To handle a more efficient, compact design of the ion trap, a new optical imaging system has been developed. The resulting instrument will enable us to study reactions between ions and radicals with unprecedented control over the reaction parameters. We will be able to study these reaction systems with exceptional sensitivity, as we can monitor the reactions of single ions. No other instrument combines a cryogenic ion trapping environment with optical access, mass spectrometry detection capabilities, and a source of cold radical reactants.