X-RAY PHOTOELECTRON SPECTROSCOPY SECONDARY ION MASS-SPECTROMETRY OF FERU ALLOY CATALYSTS

XPS/SIMS investigation of unsupported FeRu alloys has shown that the reduced and passivated surface contains an iron phase in addition to the alloy phase. Carefully controlled SIMS studies produced smooth correlations of Ru+ and Fe+ yields with composition and indicate iron enrichment of the surface. Strong FeRu+ ion yields, expected for intimately mixed surfaces, demonstrate the sensitivity of SIMS to local atomic structure. Chlorine impurities, present on the surface in significant amounts, were not removed by H2 reduction at 823 K. The results suggest that chlorine impurities may affect chemisorption results and that the passivated surface of FeRu alloys is partially covered by thin islands of iron oxide. © 1979.