A scanning probe and quartz crystal microbalance study of the impact of C60 on friction at solid-liquid interfaces

We have investigated the changes in interfacial friction of toluene on mica and Ag(111) both in the presence and in the absence of interfacial C-60 layers employing atomic force microscope (AFM) and quartz crystal microbalance (QCM) techniques. The lateral force measurements fail to detect C-60 at the toluene/mica interface, presumably because the C-60 is dislodged by the slow-moving probe tip. In contrast, QCM measurements of interfacial friction and slippage for toluene/Ag(111) are sensitive to the presence of interfacial C-60 We see the friction double when C-60 is present. The results are discussed in the light of the full-slip boundary condition which had been previously reported for surface forces apparatus (SFA) measurements on toluene/mica in the presence and absence of interfacial C-60.