Fig. 1

STM images (86 nm × 86 nm) of the single-crystal Ru(0001) sample at different stages of Au film growth: a the initial clean metallic substrate; sample bias voltage: U = + 0.1 V, tunneling current: I = 10 nA. b 5 ML Au film; U = − 0.05 V, I = 1 nA. c 9 ML Au film; U = 0.01 V, I = 1 nA. All images are presented in an identical gray scale (height-to-color correspondence), which is given rightmost. The height-distance cross-sections along the dashed lines are presented below every image. The meaning of designations within the images: “t” — atomically flat terraces, “s” — single atomic steps, “b” — locations above the buried argon bubbles, “×” — height level of the atomic layer corresponding to nominal coverage, “−” — one atomic layer below the nominal, “+” — one atomic layer above the nominal