Chemisorption of O 2 and N 2O on Cu/Ru(001)

Abstract

The interaction of O 2 and N 2O are compared on the basal plane of Ru as a function of the coverage of copper. Dissociative N 2O uptake (N 2O(g) → O(a) + N 2(g)) on clean Ru was measured using AES and transient partial pressures. The initial dissociative reaction probability is a steadily declining function of temperature while the saturation uptake of oxygen remains constant from 300–900 K. The saturation oxygen AES signal for N 2O chemisorption was one half that observed for O 2 chemisorption. The presence of 0.02 monolayers of Cu retards the initial dissociative adsorption of N 2O by 40% but has little effect on the total uptake of oxygen. The initial dissociative sticking coefficient for O 2 is not retarded significantly by small amounts of copper. Deposition of larger amounts of Cu leads to the completion of a 2D overlayer before growth in 3D begins. Surfaces covered with less than 3 monolayers of Cu exhibit larger O 2 sticking coefficients and greater oxygen stability than pure Cu.