Fig. 3
On-surface synthesis of polycyanine chains. a Overview STM image of the polycyanine chains, taken after deposition of 5.8 layers of ADN on Ag(111) at 300 K followed by annealing to 450 K. The white vectors indicate the three high-symmetry directions of the substrate. The yellow arrows indicate protrusions attributed to chain segments that are uplifted for sterical reasons (see Supplementary Fig. 8 for details). b Magnified STM image of a single chain observed in the sample of a. c, e Top and side views of the DFT-calculated adsorption model of the polycyanine chain on a Ag(111) slab. The adsorbate-induced vertical displacement of the top-layer Ag atoms is illustrated with a gray scale in c. The distances of the N atoms in the pyrrole ring (Nring) and the aza-bridging N atoms (Nbridge) with respect to the non-corrugated surface plane as well as the inter-plane angle α between the alternating benzodiiminoisoindoline moieties (see Supplementary Fig. 11 for a definition of α) are shown in e. d Comparison of the DFT-calculated (left) and experimental (right) STM images of the polycyanine chain on Ag(111). A molecular model of the polycyanine chain is overlaid in the central part. Black spheres represent carbon atoms; blue, nitrogen; white, hydrogen; gray, silver. Tunneling parameters: a, U = −3.6 V, I = 0.14 nA; b, U = 0.20 V, I = 0.10 nA; d, U = 0.55 V, I = 0.06 nA. Scale bars, a, 15 nm; b, 3 nm
