A surface X-ray diffraction study of the Rh(100) (2x2)-O reconstruction

The 0.5 ML oxygen-induced reconstruction of the Rh(100) surface has been investigated using surface x-ray diffraction. The rhodium atoms in the surface layer adopt a “clock” reconstruction with an in-plane displacement of the surface-layer Rh atoms of dRhxy=0.19±0.02 Å. The oxygen atoms were found to be situated in the “diamond” site rather than the rotated fourfold hollow site, with an in-plane displacement of 0.20±0.05 Å on either side of the center. This work supports the conclusions of recent density-functional theory and low-energy-electron-diffraction work.