Fig. 4: Dimethylene-dihydroindenofluorene intermediate 4.
a, c STM images of two polymer segments after annealing the sample to 215 °C, the former displaying a chain termination. b, d–g Constant-height frequency shift nc-AFM images with a CO functionalized tip of the segments in (a) and the highlighted part in (c), respectively. h Constant-current frequency shift nc-AFM image with a CO functionalized tip of the segment highlighted in (c). i Molecular scheme of a repeating unit of 4. j–m, Laplace-filtered images. n, o Simulated nc-AFM images of a trimer 4. Scanning parameters: a It = 100 pA, Vb = ‒0.1 V; b Δz is 160 pm above the STM set point (It = 100 pA, Vb = ‒5 mV). c It = 200 pA, Vb = ‒20 mV; d, g Δz above the STM set point (It = 100 pA, Vb = ‒5 mV) is given for each image. h It = 150 pA, Vb = ‒5 mV. Temperature in (a) indicates the sample annealing temperature, imaging was performed at 4.7 K.
