Structure of a thin oxide film on Rh(100)

The initial oxidation of Rh(100) has been studied using high resolution core level spectroscopy, low energy electron diffraction, surface x-ray diffraction, scanning tunneling microscopy, and density functional theory. We report a structural study of an oxygen induced structure displaying a $c(8\ifmmode\times\else\texttimes\fi{}2)$ periodicity at an oxygen pressure above ${10}^{\ensuremath{-}5}\phantom{\rule{0.3em}{0ex}}\mathrm{mbar}$ and using a sample temperature of $700\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. Our experimental and theoretical data demonstrate that this structure is due to the formation of a thin surface oxide with a hexagonal trilayer $\mathrm{O}\ensuremath{-}\mathrm{Rh}\ensuremath{-}\mathrm{O}$ structure.