Schematic view of the AFMIR contact (left panel) and tapping (right panel) modes. The interaction potential normal to the surface is illustrated (blue line). The approximate excursion ranges on this interaction potential for the two AFM modes are shown in yellow. In contact mode, the tip of the cantilever probe is in close contact with the surface and explores mainly the repulsive potential. In tapping mode, the cantilever oscillates and approaches the surface only for a short time, oscillating back and forth on the potential curve.