Interaction of energetic particles with ice surfaces: molecular dynamics simulation using the REAX potential

高能粒子辐射与冰表面的相互作用对于空间科学的研究特别有意义。在我们的太阳系中，卫星和彗星的表面受到粒子的照射。此外，宇宙辐射与小冰团（尘埃粒子）的相互作用也是相关的。最近的空间飞行任务-如前往丘留莫夫-格拉西缅科彗星的ROSETTA使命-使人们注意到冰表面的物理和化学性质。此外，这些研究与质谱分析技术有关，其中通过西姆斯（二次离子质谱）研究冰冷的生物样品或将反应性物种封闭在惰性冰基质中（基质隔离光谱）。本计画的目的是利用分子动力学模拟来增进我们对高能粒子与冰面相互作用的了解。这些过程与空间科学有关;其中包括太阳风、磁层离子和宇宙辐射与行星和卫星的冰表面、彗星和被冰覆盖的尘埃颗粒的相互作用。现代REAX势允许模拟控制能量碰撞的排斥相互作用和分子固体中的键，例如将用于本项目的冰混合物。因此，模拟碰撞期间和之后发生的键离解和键形成，以及通过反应形成新分子，变得可行。在这个项目中，我们的目标是获得新的理论信息的修改和溅射侵蚀的冰表面粒子辐照。要研究的典型情况包括与太阳风、木星磁层和宇宙辐射中所含离子的相互作用。

The interaction of energetic particle radiation with ice surfaces is of interest in particular for investigations in the space sciences. In our solar system the surfaces of moons and comets are subject to particle irradiation. Furthermore, the interaction of cosmic radiation with small ice clusters (dust particles) is relevant. Recent space missions - such as the ROSETTA mission to comet Churyumov-Gerasimenko - directed attention to the physics and chemistry of ice surfaces. In addition, such studies are relevant for the analytical technique of mass spectrometry, where either icy biological samples are studied by SIMS (secondary ion mass spectrometry) or reactive species are enclosed in an inert ice matrix (matrix isolation spectroscopy). The objective of this project is to use molecular dynamics simulation for enhancing our understanding of the interaction of energetic particles with ice surfaces. Such processes are relevant for the space sciences; they include the interaction of the solar wind, of magnetospheric ions and of cosmic radiation with the icy surfaces of planets and moons, comets and ice-covered dust particles. Modern REAX potentials allow to model both the repulsive interaction governing energetic collisions and the bonds in molecular solids, such as in the ice mixtures that will be used in this project. Thus the simulation of bond dissociations and formations occurring during and after impact, and hence also the formation of new molecules by reactions, become feasible. In this project we aim at obtaining novel theoretical information on the modification and sputter erosion of ice surfaces by particle irradiation. Typical scenarios to be studied include the interaction with ions contained in the solar wind, in the magnetosphere of Jupiter and in the cosmic radiation.