RUI: Optical studies of pseudoelastic nanoparticle deformation

纳米科学是研究当你将材料的尺寸减小到小于人类头发宽度的千分之一时所产生的独特性质的科学。在这些研究产生的许多令人兴奋的新现象和应用中，特别令人感兴趣的是纳米材料显示出与其大块对应物截然不同的机械性能。例如，金属纳米颗粒可以变形得更远，并从比一大块相同金属大得多的应变中恢复。该项目研究这种称为伪弹性的特性，以了解其起源，机制和局限性。包括PI和本科生团队在内的研究人员正在使用一种新的非侵入性方法来测量金纳米颗粒的机械性能如何随其尺寸变化。这种理解将使材料的设计具有令人兴奋的新机械性能，如异常高的强度，自我修复的能力，或报告是否损坏的能力。此外，本研究介绍了本科生学者，在研究团队和PI的课堂上，在纳米技术的前沿课题。PI还将研究成果转化为教育材料，向从中学到大学的学生介绍物理和化学对新技术设计的重要性。技术摘要金属纳米颗粒和纳米结构金属在现代电子，结构和生物医学材料中越来越重要。为了预测当前使用的器件的行为以及设计不断改进的应用，需要深入了解纳米结构金属的机械性能。该项目研究金属纳米颗粒变形的热力学和动力学，以更好地理解纳米尺度下发生的独特机械现象。特别是，研究人员正在利用金属纳米颗粒机械表征的新方法来研究伪弹性，这是一种独特的纳米级现象，金属纳米颗粒可以从非常大的机械变形中恢复。通过全光学测量，研究小组正在研究这种有趣行为的尺寸依赖性，以确定小金属纳米颗粒的变形和形状恢复机制。这项研究是在一个主要的本科院校进行的，因此也向本科研究人员团队介绍了纳米技术的前沿研究课题和技术。研究团队还积极参与开发课程材料和基于研究的推广活动，以介绍更广泛的学生受众，从中学到大学，该奖项反映了NSF的法定使命，并被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准。

Non-Technical AbstractNanoscience is the study of the unique properties that arise as you decrease the size of materials to less than a thousandth of the width of a human hair. Among the many exciting new phenomena and applications that have come out of such studies, one of particular interest is that nanoscale materials show vastly different mechanical properties than their bulk counterparts. For example, metal nanoparticles can deform much further and recover from much larger strains than a large piece of the same metal. This project studies that property, called pseudoelasticity, in order to understand its origins, mechanisms and limitations. The researchers, including the PI and team of undergraduate students, are using a new, non-invasive approach to measure how the mechanical properties of gold nanoparticles change with their size. This understanding will enable the design of materials with exciting new mechanical properties like unusually high strength, the ability to heal themselves, or the ability to report if they are damaged. In addition, this research introduces undergraduate student-scholars, on the research team and in the PI’s classroom, to cutting-edge topics in nanotechnology. The PI is also translating the research into educational materials to introduce students from middle school through college to the importance of physics and chemistry for the design of new technologies.Technical AbstractMetallic nanoparticles and nanostructured metals are increasingly important in modern electronic, structural and biomedical materials. An in-depth understanding of the mechanical performance of nanostructured metals is needed in order to both predict the behavior of devices currently in use as well as to design ever-improved applications. This project investigates the thermodynamics and kinetics of deformation in metal nanoparticles in order to better understand the unique mechanical phenomena that occur at the nanoscale. In particular, the researchers are taking advantage of new approaches to mechanical characterization of metal nanoparticles in order to study pseudoelasticity, a unique nanoscale phenomenon in which metal nanoparticles can recover from very large mechanical deformation. Through all-optical measurements, the research team is examining the size dependence of this intriguing behavior in order to determine the mechanism of deformation and shape recovery in small metal nanoparticles. The research is carried out at a primarily undergraduate institution, and as such is also introducing the team of undergraduate researchers to cutting-edge research topics and techniques in nanotechnology. The research team is also actively involved in developing course materials and outreach activities based on the research in order to introduce a broader audience of students, from middle school through to college, to the importance of fundamental physical and chemical phenomena in the design of new technologies.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.