Figure 7.

Force vs distance profile of an interfacial region with two clusters: each one showing repulsive and attractive regions. The full line is the adjusted dielectric permittivity profile. For the interval x = 0 up to x ≅ 12 nm there is an attraction on the tip, followed by a repulsion acting on the tip up to 24 nm, which corresponds to ε < 6. The oscillating profile of the dielectric permittivity is shown by the full line.