Dynamic Friction of Nanoscale Sliding on a C₆₀ Deposited Film

Abstract

We measured the frictional behavior acting on C₆₀ films at a small normal load as a function of oscillation amplitude using a MHz-range quartz crystal resonator and an optical AFM cantilever. The frictional behavior for C₆₀ films varies by the amplitude: For the amplitudes smaller than the C-C bond length of the C₆₀ molecule, the dynamic frictional force is directly proportional to the amplitude, while it becomes almost constant for larger amplitudes. Although the observation is in qualitatively the same manner as HOPG, the dynamic frictional force for small amplitudes is significantly larger than that of HOPG. This difference suggests that C₆₀ molecules easily tilt and/or rotate when the tip slides in C₆₀ films, and the dynamic friction arises from the tilting and/or rotating motion. [DOI: 10.1380/ejssnt.2015.135]