Growth and structure of an ultrathin tin oxide film on Rh(111)

The oxidation of submonolayer tin films on a Rh(111) surface by O-2 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 degrees C and a partial pressure of 2 x 10(-7) mbar O-2. The tin oxide film had (2 x 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. (C) 2011 American Institute of Physics. [doi:10.1063/1.3537871]