Quartz Crystal Microbalance Studies of Atomic Scale Friction

****技术摘要**** 20世纪后期标志着摩擦学基础领域的复兴，这是由能够研究原子尺度几何摩擦的新实验和理论技术引发的。该项目涉及使用一种这样的技术，即石英晶体微天平（QCM），以利用石墨烯和C60材料作为QCM上形成的样品的非凡最新进展来探索该领域的关键主题。第一项研究将建立理论的有效性，预测固定在C60基板上的晶格气体系统的重要新物理现象。钉住吸附系统中的新型晶体状态可能揭示有关二维固体有序的有趣信息，甚至可能揭示氦物质的新型超固相。第二项研究将记录滑动吸附膜中摩擦加热效应与摩擦加热导致膜蒸发时发生的冷却之间的微妙平衡。第三项研究将记录外部磁场可用于控制原子尺度摩擦的条件，并代表该领域从被动表征到主动外部控制的重大转变。一个免费的教育组成部分包括：(1)研究生和本科生持续参与研究，(2)通过讲座和书面评论直接向普通受众传播有关摩擦的最新信息。****非技术摘要****随着能源价格的上涨，节约能源和原材料的需求变得越来越迫切，物理学家们急于了解基本的能量损失过程。20世纪后期标志着摩擦学（研究摩擦和磨损）基础领域的复兴，这是由一些新的实验和理论技术引发的，这些技术能够在小到原子的尺度上研究摩擦力。该项目涉及三项研究，使用石英晶体微天平（QCM）技术，利用石墨烯和C60材料的非凡最新进展，探索该领域的关键主题。第一个是研究理论的有效性，这些理论预测了钉住原子的重要新物理现象，可能还有物质的新型零摩擦“超固体”相。第二个是研究摩擦加热效应和当摩擦加热导致薄膜蒸发时发生的冷却之间的微妙平衡。第三项研究表明，在类似于宏观磁悬浮效应的条件下，外部磁场可以用来控制原子尺度的摩擦。研究生和本科生将参与研究的各个方面。学生毕业时将拥有大量的实验和理论知识，这些知识将使他们在远远超出当前主题的许多技术领域中解决具有挑战性的社会问题。

****Technical Abstract****The late 20th century marked a renaissance in fundamental areas of tribology, sparked by new experimental and theoretical techniques capable of studying the friction in atomic-scale geometries. This project involves the use of one such technique, namely the Quartz Crystal Microbalance (QCM), to probe critical topics in this field, taking advantage of extraordinary recent progress in graphene and C60 materials as samples formed on the QCM. A first study will establish the validity of theories that predict important new physics phenomena for lattice gas systems pinned in place on C60 substrates. Novel crystalline states in the pinned adsorbed systems may reveal interesting information about the ordering of a 2D solid, and even, perhaps, a novel supersolid phase of matter for helium. A second study will document the delicate balance between frictional heating effects in sliding adsorbed films, and the cooling that occurs when frictional heat causes the films to evaporate. The third study will document the conditions under which external magnetic fields can be used to control atomic scale friction, and represents a major transition in this field from passive characterization to active external control. A complimentary educational component includes (1) ongoing participation of graduate and undergraduate students in the research, and (2) direct dissemination of state-of-the-art information on friction to general audiences through lectures and written reviews.****Non-Technical Abstract****As the price of energy rises, and the need to conserve both energy and raw materials becomes increasingly urgent, physicists' rush to understand basic energy loss processes is accelerating. The late 20th century marked a renaissance in fundamental areas of tribology (the study of friction and wear), sparked by a number of new experimental and theoretical techniques capable of studying the force of friction at scales as small as an atom. This project involves three studies using one such technique, the Quartz Crystal Microbalance (QCM), to probe critical topics in this field, taking advantage of extraordinary recent progress in graphene and C60 materials that are now widely available. The first is a study of the validity of theories that predict important new physics phenomena for pinned atom and possibly a novel zero-friction "supersolid" phase of matter. The second is a study of the delicate balance between frictional heating effects and the cooling that occurs when frictional heat causes the films to evaporate. The third study documents the conditions under which external magnetic fields can be used to control atomic scale friction, in analogy with macroscopic magnetic levitation effects. Graduate and undergraduate students will participate in all aspects of the research. The students will graduate with an arsenal of experimental and theoretical knowledge that will prepare them to attack challenging societal problems in a host of technical areas far beyond the present topic.