Figure 5
Theoretically determined stable configurations of an AFM tip in contact with a nanobubble for the case (a) when \({F}_{load} < 0\) (tip lifts the bubble), and (b) when \({F}_{load} > 0\) (tip presses onto bubble). The orientation of the tip is specified by the angle \(\varphi \) of its symmetry axis. (c) illustrates the stability on the side of \(\theta > 0\) for \(0 < l{F}_{cap} < \mu \) (left) and \(l{F}_{cap} > \mu > 0\) (right). While both configurations have zero net force and torque, when ϕ is increased infinitesimally by dϕ > 0, dτ z < 0 on the left causes dϕ to diminish, whereas dτ z > 0 on the right causes dϕ to grow.
