The Emergence of Metallic Properties in Free Metal Clusters: Ground- and Metastable States

自由金属团簇中金属特性的出现：基态和亚稳态

• 批准号: 1308835
• 负责人: Walter De Heer
• 金额: $ 60万
• 依托单位: Georgia Tech Research Corporation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-06-01 至 2021-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1308835&HistoricalAwards=false
• 关键词: Emergence; Metallic; Properties; Free; Metal

****Technical Abstract****This project studies how metallic properties develop as a function of size in clusters of atoms from a single atom to a few hundred atoms. A laser produced metal vapor cloud condenses into clusters in cryogenically cooled helium, producing a molecular beam of ultra cold clusters that are deflected in static and oscillating electric and magnetic fields. From their response the electronic properties of these clusters, in the ground state and in excited states, will be determined, revealing the evolution of superconductivity, the Kondo effect, metal conductivity and ferromagnetism is as a function of atomically precise size and composition. The understanding of these metallic properties on the nanoscale is vital for nanoscience and nanotechnologhy. The research provides undergraduate and graduate students with an exquisite opportunity to be active in frontier science while learning a wide variety of experimental techniques. ****Non-Technical Abstract****Many properties of metals, why and how some are magnetic, how they conduct electricity, and what makes some become superconductors at low temperatures are reasonably well understood in bulk samples. But single atoms of these metal have none of these properties. This project will reveal how these bulk metal properties evolve from atomic properties in clusters of metal atoms. A unique apparatus has been developed that can produce these metal clusters in high vacuum and measure them one at a time to determine how they respond to magnetic and electric fields. By measuring the forces that these fields exert on the clusters with precise knowledge of their size and composition, the evolution of metal properties can be determined. This knowledge is vital for fundamental science as well as for nanotechnology. The research also provides undergraduate and graduate students with an excellent opportunity to be active in frontier science while learning a wide variety of experimental techniques.

****技术摘要****该项目研究金属性能如何随着原子簇（从单个原子到数百个原子）的尺寸而变化。激光产生的金属蒸气云在低温冷却的氦气中凝结成簇，产生超冷簇分子束，该分子束在静态和振荡电场和磁场中偏转。根据它们的响应，将确定这些团簇在基态和激发态下的电子特性，揭示超导性、近藤效应、金属电导率和铁磁性的演变是原子精确尺寸和成分的函数。了解纳米尺度上的这些金属特性对于纳米科学和纳米技术至关重要。该研究为本科生和研究生提供了积极参与前沿科学的绝佳机会，同时学习各种实验技术。 ****非技术摘要****金属的许多特性，为什么某些金属具有磁性以及如何具有磁性，它们如何导电，以及是什么使某些金属在低温下成为超导体，这些都可以在散装样品中得到很好的理解。但这些金属的单个原子不具有这些特性。该项目将揭示这些块体金属特性如何从金属原子簇中的原子特性演变而来。一种独特的设备已经开发出来，可以在高真空中生产这些金属簇，并一次测量一个，以确定它们对磁场和电场的响应。通过测量这些场对团簇施加的力，并精确了解团簇的大小和成分，可以确定金属特性的演变。这些知识对于基础科学和纳米技术至关重要。 该研究还为本科生和研究生提供了积极参与前沿科学、同时学习各种实验技术的绝佳机会。