The oxidation of submonolayer tin films on a Rh(111) surface by O2 gas was studied using low energy electron diffraction, Auger electron spectroscopy, x-ray photoemission spectroscopy (XPS), and scanning tunneling microscopy. A uniform tin oxide monolayer film formed at oxidation temperatures around 500 °C and a partial pressure of 2×10-7 mbar O2. The tin oxide film had (2×2) periodicity on the Rh(111) surface, and the resulting tin coverage was determined to be 0.5 ML. Using XPS, the compositional ratio O/Sn was determined to be 3/2. XPS spectra showed a single component for the Sn and O peaks, indicating a uniform bonding environment. Finally, ab initio density-functional theory total energy calculations and molecular dynamics simulations were performed using the projector augmented wave method to determine the detailed structure of the tin oxide thin film.
Corresponding author: Junji Yuhara. Reprints also available from M. Schmid (schmid).
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