Mn-induced NO dissociation on Pd(1 0 0)

The changes in the NO adsorption properties of Pd(1 0 0) due to the addition of Mn have been investigated using high resolution core level photoelectron spectroscopy. The Pd(1 0 0) surface was modified by forming a c(2×2)-PdMn surface alloy at two different Mn coverages, giving surfaces partly and fully alloyed, respectively, as shown by scanning tunneling microscopy. NO adsorption on the alloy films was found to destroy the c(2×2) structure. Dissociation of the NO molecules upon heating is observed, in stark contrast to NO on the clean Pd(1 0 0) surface from which all the molecules desorb intact upon heating. The dissociation process on the c(2×2)-PdMn–(1×1)-Pd mixed surface is completed at a significantly higher temperature than for the homogeneous c(2×2) surface. It is suggested that Mn atoms give rise to NO dissociation at lower temperatures, whereas Pd atoms situated at c(2×2)-(1×1) boundaries are responsible for the NO decomposition at higher temperatures.