Anomalous Corrugation Height of Atomically Resolved AFM Images of a Graphite Surface

To clarify the origin of the anomalous corrugation height of atomically resolved AFM images of graphite under strong repulsive (contact) force, we carefully investigated the variation of the force between the lever and a graphite surface during lateral scans. For a weak repulsive force (∼1.3×10 -7 N), the variation of the force was rather smooth, where the deduced corrugation heights were ∼0.2 Å. On the other hand, for a strong repulsive force (∼2.2×10 -6 N), the variation of the force was spikelike, where the maximum corrugation heights of ∼1.7 Å were determined. We also found that the direction of the spikelike force modulation depends on the scanning direction of the sample. Observed variation of the force seems to be evidence that this anomalous large corrugation height of ∼1.7 Å is induced by the stick slip motion between the lever and a graphite surface.