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G. Ranga Rao, Y. Kadowaki, H. Kondoh, and H. Nozoye
[Surf. Sci., Vol.327, pp.293-300, 1995]
Vapor deposited Sm on a Ru(001) surface at 500 K has been investigated by X-ray photoelecton spectroscopy (XPS), temperature programmed desorption spectroscopy (TPD) and work function measurements. The development of a first monolayer can be described as simple adsorption of Sm on the Ru(001) surface. At higher coverages, intermixing of Sm and Ru occurs leading to the formation of a SmRu alloy. The formation of an interfaciall alloy above 1 ML coverage is confirmed by Ru 3d core-level photoemission (Fig. 1). The average valency of Sm in the alloy phase is determined. Temperature dependent experiments indicate the formation of two alloy phases at the 400-700 and 700-800 K regions. TPD data indicate the zero-order desorption of Sm. Work function changes show that there is a significant amount of charge transfer from Sm atoms to the Ru substrate at low coverages.
Fig. 1. Ru 3d core-level spectra after depositing the specified amounts of Sm on Ru (001) at 500 K.