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

本提案要求资助杜克大学物理系Horst Meyer博士与首尔国立大学物理系Insuk Yu博士进行为期24个月的固体氢和氘（H， HD和D）的实验和理论核磁共振（NMR）研究。研究将集中在(1)更好地理解D单晶中的核磁共振“固体回波”模式；(2)系统地研究了固体H和D中的2个“受激回波”，可以提供有关分子波动率的有价值的信息；(3)了解了氢和氢之间质子谱位移的各向异性。固体H和D各由两种分子组成，形成均匀的混合物。这两种物质的旋转角动量分别为J=1和J=0。这些物质的混合物可以按任何比例配制。J=1的分子具有电四极矩，而J=0的分子是球对称的。J=1粒子之间的各向异性力在低于约3开尔文的温度下产生取向有序。这些分子固体中的排序过程类似于稀磁系统，是J=0浓度的函数。当临界浓度J=1大于约53%摩尔时，有一个明确的向有序态的跃迁。该研究将尝试对氢、HD和D的取向排序过程提供更定量的理解，并解释在之前的固体氢核磁共振研究中观察到的异常行为。美国和韩国的合作者都是在该领域取得成功的备受尊敬的科学家。他们过去的合作导致了几份联合出版物。由于首尔大学还没有低温设备，所以韩国的工作将主要是理论工作，而杜克大学的工作将是实验和理论工作。目前的项目将允许合作者结合他们的才能和利益，互惠互利。该项目与美韩合作科学项目的目标相关，该项目旨在通过科学信息、思想、技能和技术的交流以及在互利问题上的合作，提高美韩科学家和工程师之间的合作水平。韩国参与该项目，包括Yu博士访问杜克大学，得到了韩国科学与工程基金会（KOSEF）的支持。

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).