Thermal desorption spectroscopy study of NO adsorption on the clean and Cs-precovered Ru(10(1)over-bar0) surfaces

The adsorption of NO on the clean and Cs-precovered Ru(10 (1) over bar 0) surfaces has been studied by means of thermal desorption spectroscopy (TDS). For NO adsorption on the clean surface, two adsorption states (a(1), a(2)) for the desorption temperatures at 325 degrees C and 550 degrees C were observed. In the case of NO adsorption on the Cs-precovered Ru(10 (1) over bar 0) surface, the existence of Cs resulted in more adsorption sites for at states, and the desorption temperature of this state was also increased. Furthermore, the desorption species such as N-2 and N2O were observed. This implies that part of NO molecules dissociate into N and O adatoms on the surface, and those adsorbed species recombine into N-2 and N2O. This result gives evidence for the promoting effect of alkali-metals.