US-Federal Republic of Germany Cooperative Research: Experimental Studies of Helium Microclusters

该奖项支持Jan A教授。诺思比大学 罗得岛与J.彼得教授合作研究 位于哥廷根的马克斯·普朗克流动研究所的托尼斯说， 西德国。 他们正在合作研究 在低温自由射流中形成的微观氦团簇 扩展。 他们的方法包括生产和研究氦 美国实验室的团簇离子和 德国实验室，然后比较结果。 他们的广泛目标 研究的目的是研究宏观现象的演变， 特别是超流性，随着原子数量的增加。 他们的 目前的努力集中在开发技术， 产生和表征氦团簇束， 可以预期偏离宏观行为的范围。 德国实验室有两台分子束机器， 氦团簇实验和独特的适合于拟议的 合作研究;然而，他们最近才开始 用的是浓缩氦 诺斯比教授对 稀有气体团簇最初形成为离子的经验， 得益于汤尼博士在分子束研究方面的专长。 的 调查人员的专业知识和设施相辅相成， 非常强的合作机制。 原子团簇形成了原子性质和原子结构之间的桥梁。 大体积的性质。 对尺寸依赖性研究的兴趣 各种材料的团簇的性质急剧增长， 在过去的十年里。 从实验的角度来看， 通过自由射流膨胀技术的发展， 集束光束 从理论上讲， 由于计算机能力的巨大发展， 详细的从头计算的性质相当大的 有限系统 拟议的研究将导致根本性的新的 理解超流性和物质的过渡， 原子态转变为大块态。 这可能有一个实际的副产品， 薄膜生长和其他领域。

This award supports Professor Jan A. Northby of the University of Rhode Island for collaboration in research with Professor J. Peter Toennies of the Max Planck Institute for Flow Research in Gottingen, West Germany. They are collaborating in the study of the properties of microscopic helium clusters which are formed in cryogenic free jet expansions. Their approach involves producing and studying helium cluster ions at the U.S. lab and neutral helium clusters at the German lab, then comparing results. The broad objective of their research is to examine the evolution of macroscopic phenomena, in particular of superfluidity, as the number of atoms increases. Their current efforts are concentrated in developing the technology for producing and characterizing helium cluster beams covering the size range where departures from macroscopic behavior can be expected. The German laboratory has two molecular beam machines dedicated to helium cluster experiments and uniquely suited to the proposed collaborative research; however, they have only recently begun working with condensed helium. Professor Northby has had considerable experience with rare gas clusters initially formed as ions and has benefited from Dr. Toennies expertise in molecular beam work. The complementary expertise and facilities of the investigators create a very strong collaborative arrangement. Clusters of atoms form the bridge between atomic properties and the properties of the bulk. Interest in the study of size-dependent properties in clusters of all kinds of materials has grown dramatically in the past decade. From the experimental side, this has been driven by the development of free jet expansion techniques for the production of cluster beams. From the theoretical side, growth has been driven by the tremendous expansion in computer power which now permits detailed ab initio calculations of the properties of quite large finite systems. The proposed research should lead to fundamental new understanding of superfluidity and the transition of matter from the atomic to the bulk state. This could have a practical spin-off for film growth and other areas.