No abstract

It is interesting to study the sliding direction dependence of the sliding friction for physisorbed films. Thus motivated, we carried out quarts-crystal microbalance (QCM) experiments for 4 He films adsorbed on exfoliated single-crystalline graphite. One QCM oscillated parallel to the a-axis of graphite, while the other one in the direction inclined at about 30 • with respect to the a-axis of graphite. Preliminary results show no large difference of the coupled mass between the two directions. Detailed direction and coverage dependences will be demonstrated.