Oxygen Induced Reconstruction of the Rh(100) Surface: General Tendency Towards Threefold Oxygen Adsorption Site on Rh Surfaces

Abstract

On the basis of a low energy electron diffraction $I-V$ structural investigation, the surface geometry of the $\mathrm{Rh}\left(100\right)+\left(2\times 2\right)-2\mathrm{O}$ phase has been determined. The oxygen is found to adsorb in an unusual threefold site of the rhombi created by the reconstruction of the first rhodium layer, producing a $\mathrm{pg}$ symmetry, in agreement with theoretical predictions but at variance with previous experimental conclusions. Our result indicates that there is a strong tendency of oxygen to adsorb in threefold sites on all Rh surfaces.