STM study of oxygen on Rh(111)

Oxygen chemisorption on Rh(111) has been studied by static and dynamic STM measurements. O was found to form only one ordered structure of (2 x 2) above 1.5 L exposure, contradicting previous reports of three domains of (2 x 1) structure. The maximum O surface coverage was derived to be 0.25 ML. Antiphase domains of O (2 x 2) were observed to appear on the surface, suggesting a concurrent nucleation of O on the Rh(111) surface with increasing oxygen exposure. Attractive interactions between chemisorbed O atoms lead to O island formation and O coarsening into domains of (2 x 2) ordered structure extending over the whole surface. (C) 1997 Elsevier Science B.V.