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

撞击是一个基本过程，塑造了所有行星体的表面，并通过撞击驱动的化学反应改变了其内容。迄今为止，对撞击驱动化学的研究主要集中在撞击事件后留在撞击坑内的物质，但正是在撞击羽流中-由撞击现场喷出的熔融和蒸发物质的湍流混合物组成的瞬态云-化学反应最有趣和奇异！尽管如此，撞击羽流仍然是撞击坑最不了解的方面之一-由于它们的寿命短，在实验室中很难进行研究，并且在没有重要的经验数据进行比较的情况下无法建模。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，但是发现这些方法不能探测羽流的完整化学成分，因为有些物质可能不在正在分析的光谱区域内发射，有些物质可能没有足够高的丰度来产生可检测的排放物。为了获得撞击羽流化学的完整图像，我们计划使用质谱法直接测量成分。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，其时间和质量分辨率是研究撞击羽流所必需的。通过在肯特大学的两级轻气枪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首次直接的原位测量，促进对撞击诱导的蒸发、离解和电离以及化学混合和合成进行开创性的研究。特别是，我们将研究涉及一系列水和有机物丰富的抛射体和目标的影响所产生的羽流，因为这些生命关键成分的起源对天体生物学有重大影响。

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.