Determination of Surface Stoichiometry in Polycrystalline Alloys by a Crystallographic Electron Attenuation Model - Application to the Ce/rh System

In order to obtain quantitative surface compositional information, an earlier crystallographic electron attenuation model has been extended to treat polycrystalline alloys. Simple correction factors are obtained that yield large corrections to elemental Auger intensity ratios. The model has been applied to a binary surface alloy formed by heating cerium overlayers on a polycrystalline rhodium substrate. It is shown that an alloy film is formed whose thickness is proportional to the number of Ce layers initially deposited. The surface alloy is identified as Ce3Rh2, which corresponds to a known bulk phase.