Fig. 2

STM images (86 nm × 86 nm) of atomically flat Au(111) surfaces. a, b Thin Au films grown on Ru(0001) at RT and annealed at 1050 K during 5 min; a nominal coverage 5 ML, sample bias voltage: U = − 0.2 V, tunneling current: I = 3 nA, b 9 ML, U = − 0.003 V, I = 10 nA, c single-crystal Au(111) sample; U = − 0.003 V, I = 10 nA. Please note the different gray scales given to the right of every image. The height-distance cross-sections along the white dashed lines are presented below every image. Designations: “t” — atomically flat terraces, “s” — single atomic steps, “r” — ripples, “i” — impurity cluster