Fig. 3: Stepwise transition of carbon hybridization across all three states at the linkage via annealing to elevated temperatures.
From: Visualizing stepwise evolution of carbon hybridization from sp3 to sp2 and to sp
aI–aVI Polymer 1A with the linkage L(C–C). bI–bVI, Polymer 1B with the linkage L(C=C). cI–cVI Polymer 1C with the linkage L(C≡C). STM images (aI–cI), nc-AFM images (aII–cII), BR-STM images (aIII–cIII), Laplace-filtered BR-STM images overlaid with chemical structures (aIV–cIV), Laplace-filtered BR-STM images (aV–cV) showing distinct bond angles and relative distances in three polymers, and DFT-optimized structures (aVI–cVI). Scanning parameters: (aI–cI) 200 mV, 200 pA. (aII–cII) 2 mV, Δz = 210 pm. (aIII–cIII) 2 mV, Δz = 160 pm. d DFT-calculated relative energies for corresponding configurations. The solid line presents the most possible reacting pathway, in which the species highlighted in red are observed in experiments. While dashed lines present other considered paths. e, Illustrations of the configurations in (d). DFT simulation functional: PBE + D3. Scale bar, 0.4 nm (aI–cV).
