UNIVERSITY OF CALIFORNIA, IRVINE
Grant: $443,728 - National Science Foundation - Jul. 23, 2009
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Award Description: Project Summary: Intellectual Merit: The objective of this project is to work toward a microscopic understanding of how water and dihalogen molecules interact in clusters, and in liquid and solid solutions. Gas clathrate-hydrates are crystalline solids with structures consisting of a lattice of hydrogen-bonded water molecules that encage molecules of small-diameter gas molecules. This description alone presents a fascinating idea: a hydrophobic cage in a lattice of water molecules. Gas hydrates have been the subject of research for nearly two centuries, starting with the initial detection of the chlorine hydrate in 1810 by Sir Humphrey Davy. Recent work has shown that individual water-halogen intermolecular interactions are nearly as strong as typical hydrogen bonds, and that these interactions have strong effects on the spectroscopy of dihalogen molecules interacting with water. Thus the water-dihalogen system offers an unusually rich example for using spectroscopy to understand the complexity of a condensed phase problem at the molecular level. Although the water-chlorine clathrate hydrate solid was first discovered nearly two hundred years ago, and characterized as a gas-solid solution seventy years ago, the details of how intermolecular forces and entropic effects contribute to the remarkable stability of this solid solution are yet to be understood. The water-bromine clathrate hydrates are even richer in that multiple solid structures have been identified via Raman and visible absorption spectroscopy. These solid solutions are stable above the melting point of ice even though bromine is only slightly soluble in liquid water. The work proposed here is to initiate new experimental studies of the spectroscopy of halogen-water clusters that will provide precise data for our theoretical collaborators to test model potentials that can then be applied to condensed phase simulations. We will also perform additional X-ray diffraction and spectroscopy studies on clathrate hydrate solid-solutions that will test the results of the simulations. As such, the end product will be an unusually comprehensive understanding a condensed phase system at the microscopic level. Broader Impact: The scientific knowledge produced by the proposed work will have a significant impact beyond the field of Experimental Physical Chemistry. For instance, the interaction of halogens with ice surfaces is very important for atmospheric chemistry. Although the work here aims to provide mainly fundamental, molecular level detail, such detail provides the ideas and the language that can be used to understand complex chemical systems that are important to understanding nature on the global scale. The halogen clathrate-hydrate studies will also provide insight into understanding methane clathrate-hydrates that, in turn, are the single largest deposit of terrestrial hydrocarbons. The technology for safely using methane clathrate hydrates is undergoing rapid development. If they can safely be used, this will provide a huge new energy source for the 21st century economy. However, although methane combustion yields less CO2 per joule of energy than other hydrocarbon energy sources, any new CO2 release presents a problem. Also, methane released directly to the atmosphere contributes even more to global warming, per molecule, than does CO2. Thus, providing data useful to modeling these important systems will have a significant impact on society. We chose to study the halogen hydrates first since they are more amenable to detailed experimental work. In addition to providing a deeper scientific understanding of this important problem, and training graduate students on state-of-the-art experiments and theoretical modeling, we are working to disseminate knowledge of this problem to both liberal arts college students and K-12 students. We recently published a laboratory procedure that makes propane hydrate synthesis accessible to undergraduate laboratories. We will wor
Project Description: As defined in the Award Description field.
Jobs Summary: Created: 1 Graduate Research Assistant Retained: none (Total jobs reported: 1)
Project Status: Less Than 50% Completed
This award's data was last updated on Jul. 23, 2009. Help expand these official descriptions using the wiki below.
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