Using the two-dimensional frictional force microscope, we observed two-dimensional discrete friction on the NaF(100) surface with its lattice periodicity, which is explained by the two-dimensional stick-slip model quantitatively. By the raster scan, such a discrete friction composes the lattice periodicity image of the NaF surface. This means that one of the AFM contrast mechanisms of the lattice periodicity of the ionic crystal is the discrete friction. On the other hand, with a normal load of 14 nN the discrete friction disappeared, so the number of contact atoms is estimated as a few atoms. Thus, even under a near single-atom friction regime the atomic scale friction is explained by the two-dimensional stick-slip model quantitatively.
展开▼
