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

AST-0908378约翰逊磁层和太阳风离子和电子、紫外光子、X射线和宇宙射线离子改变太阳系以及其他天体物理环境中的物质。 光子（光解）和带电粒子（辐解）引起的化学反应与气相物质的产生有关（称为解吸或溅射）。 在巨大的行星磁层、星际介质区域和年轻的恒星物体周围观察到的环境气体中，入射辐射都有贡献。 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气氛和土星磁层中的颗粒，以及木卫二和木卫三的表面和大气。 木卫二表面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物变得更加重要。 该项目将利用材料科学中的最新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嵌入的材料的组成。 工作重点将是在一些空间环境中发生的物理和化学过程的共同性，研究将影响辐射诱导材料加工的物理和化学过程，并影响材料学入门教学。 跨学科计划还与邻近的本科院校和主要为少数民族人口服务的高中进行互动。

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.