New insights into impact chemistry through light gas gun integrated in situ mass spectrometry

撞击是一个基本的过程，它塑造了所有行星的表面，并通过撞击驱动的化学反应改变了它们的内容。到目前为止，对撞击驱动化学的研究主要集中在撞击事件发生后留在撞击坑内的材料，但正是在撞击羽流中--由撞击现场喷出的熔化和蒸发物质的湍流混合物组成的瞬变云--化学反应最有趣和最奇特！尽管如此，撞击羽流仍然是撞击陨石坑最不为人所知的方面之一--它们被证明很难在实验室中进行研究，因为它们的寿命很短，而且如果没有重要的经验数据进行比较，就不可能建立模型。几个轻气炮设施目前正试图通过分析各种羽流成分发出的明亮闪光来研究撞击羽流--事实上，我们也对撞击羽流进行了光谱分析，但发现这些方法无法探测到羽流的完整化学成分，因为有些物种可能不会在被分析的光谱区域发射，有些物种的丰度可能不足以产生可探测的排放。为了获得撞击羽流化学的全貌，我们计划使用质谱学来直接测量成分。等离子体研究领域的最新技术进步导致了小体积、快速采样质谱仪的发展，具有研究撞击羽流所需的时间和质量分辨率。通过在肯特大学的二级轻气炮上安装这种最先进的飞行时间质谱仪，我们将能够对撞击羽流进行第一次直接的现场测量，从而促进对撞击诱导的汽化、解离和电离以及化学混合和合成的开创性研究。特别是，我们将研究涉及一系列水和富含有机物质的射弹和目标的撞击产生的羽流，因为这些生命关键成分的起源对天体生物学具有重大影响。

Impacts are a fundamental process, having shaped the surfaces of all planetary bodies, and modified their contents through impact-driven chemical reactions. To date, studies of impact-driven chemistry have focused on the materials that remain inside impact craters after the impact event, yet it is within the impact plume - the transient cloud comprising turbulent mixtures of molten and vaporised material ejected from the site of impact - that chemical reactions are most interesting and exotic! Despite this, impact plumes remain one of the least understood aspects of impact cratering - they have proven difficult to investigate in the laboratory due to their short lifetimes and are impossible to model without vital empirical data to compare against. Several light gas gun facilities are currently attempting to investigate impact plumes by analysing the bright flash of light emitted by various plume constituents - indeed we have also carried out spectral analyses of the impact plume but find that these methods cannot probe the complete chemistry of the plume since some species may not emit in the spectral region being analysed and some may not be present in high enough abundances to produce detectable emissions. In order to obtain a complete picture of impact plume chemistry we plan to use mass spectrometry to directly measure the constituents. Recent technological advances in the field of plasma research have led to the development of small volume, fast sampling mass spectrometers with the temporal and mass resolutions necessary to investigate impact plumes. By installing such a state-of-the-art time-of-flight mass spectrometer on the two stage light gas gun at the University of Kent, we will be able to perform the first direct, in-situ measurements of impact plumes, facilitating pioneering studies to be made of impact-induced vaporisation, dissociation and ionization, as well as chemical mixing and synthesis. In particular, we will study plumes resulting from impacts involving a range of water and organic-rich projectiles and targets as the origins of these key ingredients for life have major implications for astrobiology.