We explore the accuracy of chemical composition profiles of substitutionally disordered alloys determined experimentally by LEED (low-energy electron diffraction) I(E) analysis. We analyse experimental I(E) spectra of pure Rh(111) for its known chemical composition by comparing them to calculations assuming a substitutionally disordered PtxRh1-x alloy surface. The layer concentrations known to be 100% Rh are reproduced with a maximum error of 8% when the Pendry R-factor (RP) is employed. This error is considerably smaller than estimated by error bars derived from the variance of RP. We argue that the same accuracy can be expected for compositional depth profiles to be determined for alloys exhibiting weak chemical order and negligible lattice distortions such as PtxRh1-x.
Corresponding author: M. Schmid (schmid).
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