Figure 1. Graphene nanobubbles on Pt(111).

(a) STM topograph of graphene nanoislands grown on Pt(111) (area of 50 × 50 nm², V_s=0.5 V, I_t=0.5 nA). (b) STM topograph of graphene nanobubbles formed on graphene nanoislands (area of 25 × 25 nm², V_s=0.5 V, I_t=1 nA). (c,d) Close-up STM topograph of the graphene honeycomb lattice (area of 2.8 × 2.8 nm², V_s=0.4 V, I_t=30 nA) and nanobubble (area of 3.0 × 3.0 nm², V_s=0.03 V, I_t=30 nA), respectively. (e) dI/dV spectra obtained at a graphene nanobubble (black line) and the flat graphene area (dotted red line). To make gap more evident, we added offset to the dI/dV spectrum measured in the flat graphene area. (f) Density functional theory (DFT)-optimized structure (side and tilted top views) of Ar-implanted graphene on Pt (111). The blue, grey and cyan spheres represent Pt, C and Ar atoms, respectively. (g) z-direction displacement of each C atom from a reference atom plotted against x–y-plane-projected distance from the closest Ar atom. The reference atom is selected to be the C atom closest to the Pt surface, and each point is duplicated for the corresponding negative distance.