Fig. 2: Comparison of Lifshitz-vdW force-displacement responses in different systems.
From: Strong repulsive Lifshitz-van der Waals forces on suspended graphene

2D histograms of force-displacement responses for a gold-coated and an uncoated SiNx AFM tip approaching (a), (b) flat suspended graphene and (c), (d) SiNx-supported graphene, respectively. The dashed lines represent the last notable measured force before experiencing attraction. For (a) and (b), this corresponds to a repulsive force detected at an average displacement of 8.8 nm and 6.6 nm, respectively.