We present a scanning tunneling microscope study on reactivity of chemisorbed oxygen on the Cu(110)–(2 × 1)–O surface. We have found that the Cu(110)–(2 × 1)–O surface is intrinsically unstable under thermal annealing in the 400–900 K range. In the 455–570 K range, the surface undergoes faceting. The orientational transition of the adsorbed oxygen phase displays wide [110] terraces, covered by (2 × 1)–O bands self-assembled into a superstructure, as well as bunches of oxygen-free narrow terraces. We found that the wide [110] terraces are intrinsically unstable against further restructuring at their edges. The restructuration is driven by reversible thermal dissociation of the (2 × 1)–O bands. The slightly uneven oxygen band density between terraces, consequently differing in reactivity with respect to Cu–O fragments, induces Cu atom transport between their edges. The interplay between thermal dissociation of the (2 × 1)–O bands and long-range elastic relaxation of the strained surface is suggested to be the origin of the observed inhomogeneous oxygen distribution. In the 570–810 K range the Cu atom transport reveals continuous growth of the oxygenated [110] terraces. We discuss in detail the mechanism of the Cu transport, which results in a rapid propagation of the oxygenated terraces as well as a strain development on the surface.

• Received 12 May 2010

DOI:https://doi.org/10.1103/PhysRevB.83.075409