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Metal nanoclusters as size-resolved probes of quantum materials and phenomena

金属纳米团簇作为量子材料和现象的尺寸分辨探针

基本信息

批准号：
2003469
负责人：
Vitaly Kresin
金额：
$ 45.93万
依托单位：
University of Southern California
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2020
资助国家：
美国
起止时间：
2020-07-01 至 2024-06-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2003469&HistoricalAwards=false
关键词：
Metal nanoclusters size resolved probes

项目摘要

NON-TECHNICAL ABSTRACTLithium is the lightest metallic element. Its uses are broad: in batteries, in medication, in metallurgy and pyrotechnics, in nuclear power plants and weapons, in soaps and greases, etc. It is even a superconductor: when compressed, it carries electrical current without resistance. By being so light, lithium atoms display conspicuous quantum effects. For example, their quantum “jiggling” makes the thermal expansion of lithium metal unusually high. It is interesting and important to understand lithium’s quantum behavior, to search for its novel manifestations, and to harness it for future use. This research focuses on nanoclusters particles of lithium: aggregates of tens to hundreds of atoms which can be size-selected with atom-by-atom accuracy. By studying such microscopic metallic droplets, the research team can precisely tune their properties and select the most promising quantum configurations. The project’s aim is to (i) explore in detail the thermal expansion of lithium; (ii) produce lithium nanoclusters which become magnetic when heated (this is unusual, especially since bulk lithium is nonmagnetic); and (iii) create nanoclusters which are simultaneously oblate and prolate in shape, a unique and purely quantum effect. The graduate and undergraduate students on the team receive training in a wide range of scientific and leadership skills. In addition, the subject matter is used for fruitful outreach programs.TECHNICAL ABSTRACTThis project encompasses complementary experiments on size-, isotope-, and temperature-controlled metal nanocluster particles. It aims to reveal novel phenomena lying at the interface of nanoscale and quantum-solid behavior. The optimal material for this purpose is lithium, which displays distinctive behavior stemming from it being the lightest metallic element with the smallest electron core. Measurements on individual free particles make it possible to focus on the intrinsic properties of systems with a precisely defined size and composition and to trace the emergent physical properties from the nanoscale to the bulk. The research explores three inherently quantum phenomena: (i) Temperature, isotope mass, and cluster size dependences of thermal expansion as manifestations of the zero-point motion of ions at the nanoscale; (ii) The ability of nanoclusters to undergo quantum shape oscillations, i.e., to be in a linear superposition of two different shapes at the same time; and (iii) Temperature-induced magnetism in nanoclusters: the appearance of high-spin superparamagnetic states with increasing temperature. The experimental approach employs photoemission, photoabsorption, and Stern-Gerlach deflection of free nanoclusters. The results can serve as benchmarks for microscopic theories of electronic and lattice structure. Potential areas of applications include optical nanoelectronics, quantum sensing, and magnetic storage and detection. The project offers graduate student training in experimental and theoretical aspects of an inherently interdisciplinary field, encourages involvement by undergraduates, and serves as a fruitful resource for outreach activities.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

非技术摘要锂是最轻的金属元素。它的用途很广泛：在电池、医药、冶金和烟火、核电站和核武器、肥皂和油脂等方面，它甚至是一种超导体：当被压缩时，它携带电流而没有电阻。由于锂原子如此轻，因此显示出显著的量子效应。例如，它们的量子“抖动”使得锂金属的热膨胀异常高。理解锂的量子行为，寻找其新颖的表现形式，并利用它为未来使用是有趣而重要的。这项研究的重点是锂的纳米团簇颗粒：数十到数百个原子的聚集体，可以逐个原子精确地选择尺寸。通过研究这种微观金属液滴，研究小组可以精确地调整它们的性质，并选择最有前途的量子构型。该项目的目标是：（i）详细探索锂的热膨胀;（ii）产生加热时具有磁性的锂纳米团簇（这是不寻常的，特别是因为大块锂是磁性的）;以及（iii）创建同时具有扁圆和扁长形状的纳米团簇，这是一种独特的纯量子效应。团队中的研究生和本科生接受广泛的科学和领导技能培训。此外，该主题是用于富有成效的推广programmes.Technical摘要该项目包括补充实验的大小，同位素，和温度控制的金属纳米团簇粒子。它旨在揭示纳米尺度和量子固体行为界面的新现象。锂是实现这一目的的最佳材料，它表现出独特的行为，因为它是最轻的金属元素，具有最小的电子核。对单个自由粒子的测量使人们能够专注于具有精确定义的尺寸和组成的系统的固有特性，并跟踪从纳米尺度到体积的涌现的物理特性。该研究探索了三种固有的量子现象：（i）温度，同位素质量和热膨胀的簇大小依赖性，作为纳米尺度下离子零点运动的表现;（ii）纳米簇进行量子形状振荡的能力，即，是在一个线性叠加的两个不同的形状在同一时间;和（iii）温度诱导的磁性纳米团簇：外观的高自旋超顺磁态随着温度的升高。实验方法采用光发射，光吸收，和Stern-Gerlach偏转的自由纳米团簇。结果可以作为电子和晶格结构的微观理论的基准。潜在的应用领域包括光学纳米电子学、量子传感、磁存储和检测。该项目为研究生提供实验和理论方面的培训，鼓励本科生参与，并作为一个富有成效的资源外展活动。该奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的智力价值和更广泛的影响审查标准的支持。