Fig. 5.

(A) Semilogarithmic plot of current versus tip displacement acquired over an unsubstituted symmetric NDI cyclophane. Gray thin lines are linear fits to the transition and contact regions. Their intersection is used to define a contact distance z_c. Zero displacement (z₀) is determined by the parameters (V = 1 V, I = 1 nA) used before opening the STM feedback loop. The contact distance z_c is found to be approximately 0.052 ± 0.012 nm, for the conductance curves acquired with an initial setpoint of V = 1 V. (B) Constant-current height profiles acquired of a cyclophane island at I = 50 pA, V = 3 V (black) and I = 1 nA, V = 1 V (gray). (C) Model of the voltage drop across the vacuum gap and the cyclophane. The upper NDI of the cyclophane is lifted from the surface due to the rigid spacers in the cyclophane double structure.