Quartz Crystal Microbalance Studies of Atomic Scale Friction

*技术摘要*20世纪末标志着摩擦学基本领域的复兴，新的实验和理论技术能够研究原子尺度几何中的摩擦。该项目涉及使用一种名为石英晶体微天平(QCM)的技术来探索这一领域的关键话题，利用石墨烯和C60材料作为样品在QCM上形成的非凡最近的进展。第一项研究将建立理论的有效性，这些理论预测了固定在C60衬底上的晶格气体系统的重要新物理现象。钉扎吸附体系中的新晶态可能会揭示有关2D固体有序性的有趣信息，甚至可能揭示氦的新的超固态物质相。第二项研究将证明滑动吸附薄膜中的摩擦加热效应与摩擦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。免费教育部分包括(1)研究生和本科生持续参与研究，以及(2)通过讲座和书面评论直接向普通受众传播关于摩擦的最新信息。*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日益迫切，物理学家急于了解基本的能量损失过程。20世纪末标志着摩擦学基础领域(摩擦和磨损研究)的复兴，许多新的实验和理论技术能够在小到一个原子的尺度上研究摩擦力。该项目涉及三项研究，使用其中一项技术--石英晶体微天平(QCM)--来探索该领域的关键课题，利用目前广泛可用的石墨烯和C60材料的非凡最新进展。第一个是对理论的有效性的研究，这些理论预测了钉扎原子的重要新物理现象，以及可能出现的物质的新的零摩擦“超固态”相。第二个是研究摩擦加热效应和当摩擦热导致薄膜蒸发时发生的冷却之间的微妙平衡。第三项研究记录了外部磁场可以用来控制原子尺度摩擦的条件，类似于宏观磁悬浮效应。研究生和本科生将参与研究的方方面面。学生毕业后将拥有丰富的实验和理论知识，这些知识将为他们在许多远远超出当前主题的技术领域解决具有挑战性的社会问题做好准备。

****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.