U.S.-Korea Cooperative Research on NMR Phenomena in Solid H2and D2

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This proposal requests funds to permit Dr. Horst Meyer, Department of Physics, Duke University, to pursue with Dr. Insuk Yu, Department of Physics, Seoul National University, for 24 months, an experimental and theoretical nuclear magnetic resonance (NMR) study of solid hydrogen and deuterium (H , HD, and D ). The research 2 2 will focus on (1) a better understanding of the NMR "solid echo" pattern in D single crystals, (2) a systematic study of 2 "stimulated echoes" in solid H and D that can give valuable 2 2 information on the molecular fluctuation rates, and (3) understanding the anisotropy of the NMR shift in the proton spectrum between H and HD. Solid H and D are each made up 2 2 2 of two molecular species forming a homogeneous mixture. These two species have rotational angular momentum (J=1) and (J=0). Mixtures of these species can be prepared in any proportion. The J=1 molecules have an electric quadrupole moment, while those with J=0 are spherically symmetric. Anisotropic forces between the J=1 particles produce orientational ordering at temperatures below about 3 degrees Kelvin. This ordering process in these molecular solids, analogous to dilute magnetic systems, is a function of the J=0 concentration. Above a critical concentration of J=1 equal to about 53 mole percent, there is a well defined transition to an ordered state. The research will attempt to provide a more quantitative understanding of the orientation ordering process in H , HD, and D and to explain anomalous behavior observed in 2 2 previous NMR studies of solid hydrogen. The U.S. and Korean collaborators are highly respected scientists who have records of successful research in the field of this project. Their collaboration in the past has led to several joint publications. Because Seoul National University does not yet have low temperature facilities, the work in Korea will be mostly theoretical, while that at Duke University will be both experimental and theoretical. The present project will allow the collaborators to combine their talents and interests for mutual benefit. This project is relevant to the objectives of the U.S.-Korea Cooperative Science Program which seeks to increase the level of cooperation between U.S. and Korean scientists and engineers through the exchange of scientific information, ideas, skills, and techniques and through collaboration on problems of mutual benefit. Korean participation in the project, including Dr. Yu's visits to Duke University, is supported by the Korea Science and Engineering Foundation (KOSEF).