Fig. 4
From: On-surface synthesis of a nitrogen-embedded buckybowl with inverse Stone–Thrower–Wales topology
Structural and electronic properties of the nitrogen-embedded buckybowl 8. a Overview STM topography image of the surface after an annealing step to 320 °C, showing the presence of mostly half-closed species (7b), and the fully closed buckybowls (8) highlighted by the white circles (V = −1.2 V, I = 20 pA, scale bar: 5 nm). b High-resolution STM image of 8 acquired with a CO tip (V = −0.1 V, I = 50 pA, scale bar: 0.5 nm). c Corresponding UHR-STM image of 8, evidencing complete ring closure and presence of the ISTW topology at the core (open feedback parameters: V = 5 mV, I = 50 pA; Δz = −50 pm; scale bar: 0.5 nm). d DFT-simulated STM image of 8 (V = −0.3 V, scale bar: 0.5 nm). e Top (upper panel) and side (lower panel) views of the DFT equilibrium geometry of 8. The out-of-plane buckling of the buckybowl to assume the bowl-opening-down conformation is evident. f STS spectra on 8 showing differential conductance peaks at −1.15 V and +2.70 V corresponding to the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). A reference spectrum on Au(111) is shown in gray and serves as marker for the tip quality. The spectra are vertically shifted for clarity. Inset: STM topography image of 8 with overlaid DFT-optimized molecular model. The red and blue circles mark the positions at which the corresponding STS spectra were acquired. g, i Experimental dI/dV maps at the energies of HOMO and LUMO; and h, j corresponding DFT-simulated dI/dV maps at a tip-sample distance of 5 Å. (Open feedback parameters for the STS spectra: V = −1.6 V, I = 50 pA, Vrms = 20 mV, f = 860 Hz. Open feedback parameters for the experimental dI/dV maps: d V = −1.15 V, I = 40 pA, Vrms = 20 mV, f = 860 Hz; i V = 2.70 V, I = 40 pA, Vrms = 20 mV, f = 860 Hz.) All scale bars: 0.5 nm
