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Brian Borovsky

St. Olaf College
Friction at the atomic scale: Revealing the hidden structure of interfaces
Have you ever wondered what exactly goes on between the atoms at contacting surfaces in order to produce friction? Scientists today are very actively engaged in determining the workings of friction at the atomic scale. Such knowledge has remained tantalizingly elusive, even as new experimental methods and theoretical models have greatly expanded our understanding of surfaces over the last few decades. Friction is inherently complex and inscrutable because it involves two surfaces sandwiched together, usually with intervening layers that may act as lubricants. Such closed interfaces keep their secrets by remaining inaccessbile to experimental probes originally designed for open surfaces. In this talk, I will show how an indentation probe combined with a vibrating quartz crystal forms an apparatus capable of answering some longstanding questions about the structure of interfaces: when two surfaces that are not perfectly smooth come together, how many true points of contact form, how many atoms across are they, and how far apart? Knowledge of these small-scale details plays an important role in understanding friction and is needed to guide development of accurate theoretical models. This apparatus is also capable of studying lubricant films one molecule thick. These may prove to be essential for the ultimate success of a new generation of microscopic machines fabricated from silicon.
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