High-frequency measurements of interfacial friction using quartz crystal resonators integrated into a surface forces apparatus

A quartz crystal resonator covered with a thin sheet of mica was integrated into a surface forces apparatus. The shifts in resonance frequency and bandwidth were monitored as the mica surface came into contact with a spherical lens approached from above. We compare experiments where the lens was either coated with a second mica sheet or just had a silver layer evaporated onto its surface. For the contact with the silver surface, strong maxima in bandwidth occurred during the formation and the disruption of the contact. No such maxima were seen when approaching and separating two mica surfaces. We attribute this increased dissipation to sliding and rolling friction, involving plastic deformation of the metal surface under oscillatory load.