Interaction of CO with the SmOx/Ru(001) interface

The effect of an interface of rare earth oxide/transition metal upon CO adsorption was investigated on the Ru(001) surface partially covered with SmOx, which was prepared by means of the selective oxidation of Sm in a Sm+CO coadsorption system on Ru(001). Temperature programmed desorption and ultraviolet photoelectron spectroscopy results indicated that two characteristic adsorption states of CO presented at the interface of SmOx/Ru(001) depending on the coverage of preadsorbed Sm. For the low Sm coverage below similar to 0.3 monolayer, the interface was completely oxidized and the CO species placed at the interface site desorbed at lower temperature than that on a bare Ru site. For the higher Sm coverage, in contrast, the boundary of SmOx island was defective in oxygen and the interface of SmOx/Ru(001) yielded more tightly CO bonding state compared with the bare Ru site. (C) 1998 Elsevier Science B.V. All rights reserved.