Interpretation of the atomic scale contrast obtained on graphite and single-walled carbonnanotubes in the dynamic mode of atomic force microscopy

Abstract

Atomic scale data obtained with atomic force microscopy (AFM) in the dynamic mode ongraphite and a single-walled carbon nanotube (SWNT) are compared with simulations torelate the observed contrast to the real surface structure. The complete surface unit cell,and particularly the carbon site asymmetry on graphite, can be resolved in the attractivenon-contact regime as well as in the weakly repulsive intermittent contact regime. On anSWNT, no carbon site asymmetry is present and the contrast above neighbouring carbonatoms in the attractive non-contact regime is symmetric. The experimental results can bequalitatively reproduced using a Lennard-Jones potential and a graphene layerwith and without carbon site asymmetry to model the tip–sample interaction.