Sputtering, Radiolysis, and Photolysis: Physical Mechanisms in Astrophysical Environments

磁层和太阳风离子和电子、紫外线光子、x射线和宇宙射线离子改变了太阳系以及其他天体物理环境中的物质。由光子（光解）和带电粒子（辐射解）引起的化学反应与气相物质的产生有关（称为解吸或溅射）。在巨行星磁层、星际介质区域和年轻恒星物体周围观测到的环境气体中，入射辐射起着重要作用。因此，对中性和离子的观测可以提供有关环境中存在的物质的信息，例如土星主环上的氧气大气和土星磁层中的颗粒，以及木卫二和木卫三的表面和大气。木卫二上存在地下海洋的可能性，使得在其相对年轻的表面上描述氧化剂的辐射分解作用变得更加重要。该项目将利用材料科学领域最新的计算工具建立实用模型，从而利用气体或等离子体观测来确定嵌入辐射环境中的材料的成分。工作的重点将放在若干空间环境中发生的物理和化学过程的共性上。本研究将影响辐射诱导材料加工的物理和化学，并影响材料科学导论的教学。这个跨学科项目还与邻近的本科院校和高中进行了互动，这些学校主要为少数民族提供服务。

AST-0908378JohnsonMagnetospheric and solar wind ions and electrons, UV photons, X-rays and cosmic ray ions alter materials in the solar system as well as in other astrophysical environments. The chemistry induced by photons (photolysis) and by charged particles (radiolysis) relates to the production of gas-phase species (called desorption or sputtering). Incident radiation contributes to the ambient gas observed in giant planet magnetospheres, in regions of the interstellar medium, and around young stellar objects. Observations of neutrals and ions can therefore give information on the materials present in environments such as the oxygen atmosphere over Saturn's main rings and grains in Saturn's magnetosphere, and the surfaces and atmospheres of Europa and Ganymede. The possibility of a sub-surface ocean on Europa makes it all the more important to describe the radiolytic production of oxidants in its relatively young surface. This project will build practical models using the latest computational tools in materials science, so as to use gas or plasma observations to determine the composition of materials embedded in a radiation environment. Work will focus on the commonality of the physical and chemical processes occurring in a number of space environments.The research will impact the physics and chemistry of the radiation-induced processing of materials, and affects the teaching of introductory materials science. The cross-disciplinary program also has interactions with neighboring undergraduate institutions and high schools that primarily serve minority populations.