Adsorption of O-2 on Ag(111): Evidence of Local Oxide Formation
The atomic structure of the disordered phase formed by oxygen on Ag(111) at low coverage
is determined by a combination of low-temperature scanning tunneling microscopy and density
functional theory. We demonstrate that the previous assignment of the dark objects in STM to
chemisorbed oxygen atoms is incorrect and incompatible with trefoil-like structures observed in
atomic-resolution images in current work. In our model, each object is an oxide-like ring formed by
six oxygen atoms around the vacancy in Ag(111). The saturation coverage of the disordered phase
was found to be 0.36 ML, being six time larger than in the previous models.