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

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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.