Investigation of the Formation of Water and of the Growth of Ices on Dust Grain Analogues

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AST-0908108VidaliThis award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).This project will investigate the formation of water molecules and the growth of ice in conditions that simulate the interstellar medium and planetary environments. Water is a well-recognized prerequisite for the complex chemistry linked to the emergence and sustainability of life, and yet little is known of how water molecules actually form, although it is clear that gas-phase reactions are inadequate to explain the observed abundance of water and water-ice in space. This challenging work exploits the group's expertise and unique laboratory techniques in areas such low fluxes of reactants, hydrogen and oxygen atomic beams, mass spectrometry, in-situ infrared spectroscopy, and surface characterization probes, and involves close collaboration with a theoretical team. The program will study the mechanism and rates of water formation on grains via hydrogenation reactions and interaction with energetic particles, measure the alteration of grains early in ice-mantle formation, determine how ices grow and the effect of photo-dissociation, and evaluate the competing reactions of H with O to form water, H with H to form molecular hydrogen, and H with CO to form various different molecules. The team will also determine the deuteration rate and pathways. Theoretical analysis will use the experimentally determined parameters to obtain reaction rates in space environment conditions.This research is widely valuable for interpreting results from current and future ground- and space-based telescopes, such as the Spitzer and Herschel satellites and the Atacama Large Millimeter Array. It will provide an unprecedented understanding of the formation of water and the growth of ices. The anticipated theoretical understanding will benefit all modelers of interstellar and planetary chemistry. The project provides students with an opportunity to work in an interdisciplinary field at the forefront of research in astrophysics, planetary science and surface science. The principal investigator in particular is very active in outreach programs sponsored by local and national organizations and provides a recognized nurturing environment to undergraduate and high-school students.