Implementation of cryogenic techniques for the investigation of ion-neutral reactions in the cold regime

采用低温技术研究冷态下的离子中性反应

• 批准号: 2124805
• 金额: --
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2124805
• 关键词: Implementation; cryogenic; techniques; investigation; ion

'Cold' chemistry, that is, chemistry conducted below 1K, is an exciting and rapidly expanding field with the potential to enhance our understanding of low temperature reaction dynamics. This is a regime where the quantum nature of the reaction is expected to play an increasingly important role. Through studying this domain, we can develop a better understanding of the reaction dynamics in the coldest parts of the universe and answer problems such as the enhanced abundance of cosmic deuterium compared to the abundance in the Interstellar medium (deuterium fractionation). It will also allow us to test many theories proposed to predict patters of reactivity in this cold regime, theories that were proposed many decades ago and remain to be tested experimentally. Validation or improvement of these theories will be invaluable to the field of chemical reaction dynamics and will enable a completely novel analysis that has not been previously possible. Specifically, I will start my studies by trying to create an internally cold source of oriented ammonia (ND3) molecules using our buffer gas apparatus that is connected to a quadrupole velocity guide. A cold beam has successfully been produced with this apparatus in the past, but the vast majority of molecular orientation is lost once the beam passes through a region of zero electric field after the guide exit. Applying a field to this region (or redesigning the post-guide segment of the apparatus) will help to retain a much larger percentage of this orientation. A linear Paul ion trap is connected to the guide exit which provides us with a way of producing a translationally cold source of ions via either laser or sympathetic cooling. Connecting these two sources of cold reactants will allow us to study the effect of low temperature and molecular orientation on the rates of reaction. Further research will be by way of a new, cryogenic ion trap which is currently being developed. The goal is to attach this to the Zeeman decelerator which will provide a source of cold radicals. Using the Zeeman decelerator we will be able investigate the reactivity of radical neutral species with laser and sympathetically cooled ions which are trapped in the cryogenic ion trap. These two methods allow us to investigate the reactivity of a wide range of reactants and probe the cold regime even further than has been possible before. This project falls within the EPSRC 'Chemical Reaction Dynamics and Mechanisms' research area and will provide a novel methodology for the study of ion-molecule reactions which will align us with the EPSRCs strategic goals of establishing the UK as a world leader in this field. The techniques are of interest to both the physics and chemistry fields and will have links to many other EPSRC research areas such as 'Computational and Theoretical Chemistry' and 'Cold Atoms and Molecules', making this project of wide interest to the EPSRC and the physical chemistry community as a whole.

“冷”化学，即在1K以下进行的化学，是一个令人兴奋和迅速发展的领域，有可能提高我们对低温反应动力学的理解。这是一个机制，其中反应的量子性质预计将发挥越来越重要的作用。通过研究这一领域，我们可以更好地了解宇宙最冷部分的反应动力学，并回答诸如宇宙氘的丰度与星际介质中的丰度相比有所增加（氘分馏）等问题。它还将使我们能够测试许多理论，这些理论被提出来预测这种冷态下的反应模式，这些理论是几十年前提出的，仍然有待实验检验。这些理论的验证或改进对于化学反应动力学领域将是非常宝贵的，并将使以前不可能的全新分析成为可能。具体来说，我将开始我的研究，试图创建一个内部冷源定向氨（ND 3）分子使用我们的缓冲气体装置，连接到一个四极速度引导。在过去已经成功地用该装置产生冷束，但是一旦束在引导出口之后穿过零电场区域，绝大多数分子取向就丢失。向该区域施加场（或重新设计装置的后引导段）将有助于保持该取向的更大百分比。一个线性的保罗离子阱连接到引导出口，这为我们提供了一种通过激光或感应冷却产生冷离子源的方法。将这两种冷反应物的来源联系起来，将使我们能够研究低温和分子取向对反应速率的影响。进一步的研究将通过目前正在开发的一种新的低温离子阱进行。我们的目标是把它连接到塞曼减速器上，这将提供一个冷自由基的来源。使用塞曼减速器，我们将能够研究自由基中性物种与激光和同情冷却的离子被困在低温离子阱中的反应。这两种方法使我们能够研究各种反应物的反应性，并比以前更进一步地探测冷态。该项目福尔斯属于EPSRC的“化学反应动力学和机制”研究领域，并将为离子分子反应的研究提供一种新的方法，这将使我们与EPSRC的战略目标保持一致，即建立英国在这一领域的世界领先地位。这些技术对物理和化学领域都很感兴趣，并将与EPSRC的许多其他研究领域联系起来，如“计算和理论化学”和“冷原子和分子”，使EPSRC和整个物理化学界对该项目产生了广泛的兴趣。