β Scribed by Y. G. Shen; D. J. O'Connor; R. J. MacDonald
No coin nor oath required. For personal study only.
The interaction of O with the Ni~3~Al(001) surface has been studied using lowβenergy He^+^ scattering. Oxygen adsorption at an exposure of 10 L and a temperature of 700Β°C results in the total disappearance of the Ni ISS signal, indicating the formation of a monolayer AlO~x~ overlayer. This oxide AlO~x~ overlayer has been examined by measuring the azimuthal angle dependence of the scattered ion yield at fixed scattering angle under different coverages of oxygen. The azimuthal variations of the Ni and Al ISS signals from the Oβcovered surface are compared with those of Ni and Al from the clean surface, and the results used to derive a value for the fractional coverage of oxygen on the surface. The analysis supports the model that the oxide initially grows in the form of islands, with no influence on remaining areas of the crystal. No evidence of the ordering of the oxide islands was observed. Further evidence of the growth of the AlO~x~ surface. The results indicate that the remaining (uncovered) Ni~3~Al surface retains the crystal structure of a clean surface. The rate of growth of the AlO~x~ islands on the Ni/~3~Al(001) surface was also found to be related to temperature.
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