CAREER: The Dependence of Friction on Vibrations at the Atomic Scale: A Fundamental Study Using Isotopic Engineering

罗伯特·w·卡匹克美国威斯康辛大学麦迪逊分校研究摩擦学这门长期存在的工程学科——研究摩擦、粘附、润滑和磨损——取得了很大进展，但仍存在许多关键问题。最近，摩擦学在纳米技术领域变得至关重要，因为在小尺度上增加的表面体积比确保了表面或界面效应主导了微或纳米尺度组件之间的相互作用。因此，如果没有对界面摩擦学特性的基本原子尺度理解，纳米级材料技术的实现将不会取得进展。提出的研究将通过研究摩擦学的一个基本方面来解决这一知识差距：摩擦能量耗散与材料振动特性之间的关系。具体来说，PI将执行原子力显微镜（AFM）在原子尺度上的摩擦测量，作为滑动材料同位素组成的函数。替换较重的稳定同位素是一种通过改变材料中原子的质量而不是化学性质来定制特定振动特性的方法。本研究的影响将是：(1)提供定量的实验基础，将从振动能量的角度批判性地提高对摩擦能量耗散的理论认识；(2)通过同位素工程设计具有优化摩擦学（和其他）性能的纳米结构材料和器件。为迎接纳米技术的新机遇，工程项目必须将以前非传统的物理和实验概念纳入课程。PI将为此做出重大贡献：(1)扩大工程力学本科实验课程，包括一系列纳米尺度实验，包括原子力显微镜实验；(2)共同开发针对工程师的纳米技术高级研讨会课程。其目的不仅仅是在当地提供新的课程材料，而是让这些材料作为模型，通过评估和在网络、教育出版物和公共会议上的广泛传播来提高各地的工程课程。此外，针对普通大众和K-12学生的推广工作将继续进行。PI将通过开发显微镜，摩擦和同位素主题的模块（可视化，模型，动手材料），为即将到来的国际科学博物馆材料科学展览的设计做出贡献。PI还将开发一种教室兼容的宏观AFM，由简单和负担得起的组件制成，可以演示高分辨率成像和摩擦力测量背后的概念。这项工作的当地影响将通过PI积极参与威斯康星大学麦迪逊分校成功的少数民族大学招聘计划而感受到。最后，在PI实验室的实践基础上，实验室的工作还将包括本科生的大量参与，包括代表性不足的群体的成员。

CAREER: The Dependence of Friction on Vibrations at the Atomic Scale: A Fundamental Study Using Isotopic Engineering Robert W. Carpick University of Wisconsin - Madison Research Much progress has been made in the long-standing engineering discipline of tribology - the study of friction, adhesion, lubrication, and wear - yet many key questions remain. Recently, tribology has emerged as critically important to the field of nanotechnology, since the increased surface-to-volume ratio at small scales ensures that surface or interface effects dominate the interactions between micro- or nano-scale components. Therefore, progress toward the implementation of nano-scale materials technologies will not occur without a fundamental atomic-scale understanding of the tribological properties of interfaces. The proposed research will address this knowledge gap by studying a fundamental aspect of tribology: the relationship between frictional energy dissipation and the vibrational properties of materials. Specifically, the PI will perform atomic force microscope (AFM) measurements of friction at the atomic scale as a function of isotopic composition of the sliding materials. The substitution of heavier stable isotopes is a method to tailor specific vibrational properties by changing the mass, but not the chemical identity, of atoms in a material. The impact of this research will be: (1) to provide a quantitative experimental basis that will critically enhance the theoretical understanding of frictional energy dissipation in terms of vibrational energy; and (2) to enable the design of nanostructured materials and devices with optimized tribological (and other) properties via isotopic engineering. Education and Outreach To be prepared for new opportunities in nanotechnology, engineering programs must incorporate previously non-traditional physical and experimental concepts into the curriculum. The PI will make a major contribution to this by: (1) expanding an engineering mechanics undergraduate laboratory course to include a battery of nano-scale experiments including AFM experiments; and (2) co-developing an advanced seminar course in nanotechnology directed at engineers. The intention is not simply to provide new course materials locally, but to have these materials serve as models for enhancing engineering curricula everywhere through evaluation and wide dissemination on the web, education publications, and in public meetings. In addition, outreach efforts aimed at the general public and K-12 students will be pursued. The PI will contribute to the design of an upcoming international science museum exhibit on materials science by developing modules (visualization, models, hands-on materials) on the topics of microscopy, friction, and isotopes. The PI will also develop a classroom-compatible macro-scale AFM made of simple and affordable components which can demonstrate concepts behind high resolution imaging and friction force measurements. Local impact of this work will be felt through the PI's active involvement in a successful minority university recruiting program at UW-Madison. Finally, building on the established practice in the PI's lab, the laboratory efforts will also include substantial involvement of undergraduates including members of underrepresented groups.