Fig. 4: STM and nc-AFM images of ribbons formed through 3 coupling after annealing at 673 K and the schematics of the process.
a Large-scale STM image of the ribbons. b STM image of a W-shaped ribbon 5 acquired with a CO functionalized tip. The 5 is constructed by enantiomers with different chirality. We highlight two enantiomers with different chirality using blue and red contours. c Laplacian filtered bond-resolved nc-AFM image taken in the gray box in b. The enantiomers with different chirality are painted in light blue and light pink; the six-membered rings of carbenes are colored in light yellow; and the newly formed pentagons are filled in light green. d STM image and e Laplacian filtered nc-AFM image of side product 6. f The proposed reaction processes. The chemical structures of 5 and 6 are resolved from c and e. The carbenes of 4a and 4b are highlighted with yellow shadows. The red bonds and green shadows in 5 denote the newly formed bonds and pentagons in polymerization, respectively. The yellow shadows in 5 denote the six-membered rings of carbene. Scanning parameters: (a) Vs = −1 V, It = 10 pA; (b) Vs = −40 mV, It = 60 pA; c and e Amplitude = 100 pm; d Vs = −40 mV, It = 10 pA. Scale bars: (a) 5 nm; (b) and (c) 1 nm; (d) and (e) 0.5 nm.
