Disordered surface structure of an ultra-thin tin oxide film on Rh(100)

The composition and structure of an ultra-thin tin oxide film on Rh(100), prepared by the deposition of a submonolayer of tin followed by annealing in an O2 atmosphere, were examined by a combination of low-energy electron diffraction (LEED), Auger electron spectroscopy, X-ray photoemission spectroscopy (XPS), scanning tunneling microscopy (STM), and ab initio calculations based on density functional theory (DFT). Although the LEED pattern exhibited c(2 × 8) spots clearly, a uniform periodicity of the c(2 × 8) unit cell was not observed in the STM images. The bright dots that were observed periodically in the STM image were similar to those of the ultra-thin Sn2O3 film on Rh(111) and formed a zigzag arrangement with the numerous point and line defects. The XPS study revealed that the Sn 3d5/2 peak of the tin oxide film on Rh(100) showed a metallic state as well as an oxide state that was between the SnO2 and SnO states. The structural models, which were based on the Sn2O3 structure on Rh(111), were determ...