Penn and UC Merced Researchers Match Physical and Virtual Atomic Friction Experiments

Technological limitations have made studying friction on the atomic scale difficult, but researchers at the University of Pennsylvania and the University of California, Merced, have now made advances in that quest on two fronts. By speeding up a real atomic force microscope and slowing down a simulation of one, the team has conducted the first atomic-scale experiments on friction at overlapping speeds. The study was led by graduate student Xin-Zhou Liu and professor and department chair Robert Carpick , both of the Department of Mechanical Engineering and Applied Mechanics in Penn's School of Engineering and Applied Science, and Ashlie Martini, associate professor in UC Merced's School of Engineering, with Zhijiang Ye, a graduate student at UC Merced. Yalin Dong, a former member of Martini's research group, and Philip Egberts, then a member of Carpick's research group, also contributed to the research. Their study was published in Physical Review Letters. A phenomenon known as "stick-slip friction" is very often involved in sliding at both the macro and the atomic scales. The resistance associated with friction is the product of atomic points of between two objects being temporarily stuck together, where they remain until the applied force provides enough elastic energy for those points to break apart.