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

AST-0908378Johnson 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会改变太阳系以及其他天体物理环境中的材料。 由光子（光解）和带电粒子（辐射分解）引起的化学反应与气相物质的产生（称为解吸或溅射）有关。 入射辐射有助于在巨行星磁层、星际介质区域和年轻恒星周围观察到的环境气体。 因此，对中性粒子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描述其相对年轻的表面中氧化剂的辐射分解产生变得更加重要。 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，以便利用气体或等离子体观测来确定辐射环境中材料的成分。 工作重点是在许多空间环境中发生的物理和化学过程的共性。该研究将影响材料辐射诱导处理的物理和化学，并影响入门材料科学的教学。 该跨学科项目还与主要为少数族裔群体服务的邻近本科院校和高中进行互动。

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.