SLED-TYPE MOTION ON THE NANOMETER-SCALE - DETERMINATION OF DISSIPATION AND COHESIVE ENERGIES OF C-60

The tribological properties of C-60 on the mesoscopic scale were inves tigated with a scanning force microscope, which allowed simultaneous m easurements of normal and lateral forces under ultrahigh-vacuum condit ions. islands of C-60, deposited on NaCl(001), could be moved by the a ction of the probing tip in a controlled way. Different modes of motio n, such as translation and rotation, were observed. An extremely small dissipation energy of about 0.25 millielectron volt per molecule and a cohesive energy of 1.5 electron volts were determined in these nanom eter-scale experiments. The corresponding shear strength of 0.05 to 0. 1 megapascal was smaller by one order of magnitude than typical values of boundary lubricants. For C-60 on graphite, disruption of the islan ds was observed and collective motion of the islands could not be achi eved. These results could find use in the field of nanotechnology; for example, C-60 islands could be developed into a sled-type transport s ystem on the nanometer scale.