Adsorption dynamics of O2 on Cu(1 0 0): The role of vacancies, steps and adatims in dissociative chemisorption of O2

Adsorption dynamics experiments on Cu(1 0 0) at 300 K indicate that surface defects induced by 3.4 keV Ar+-ion bombardment strongly enhance the dissociative chemisorption probability of O2. Energy selective molecular beam surface scattering experiments reveal a defect induced low-barrier dissociation pathway leading to enhanced dissociation of O2 molecules with translational energy up to 60 meV. Density functional theory calculations attribute the decrease in O2 dissociation barrier to the weakening of O–O bond at Cu vacancies, thus resolving the contradiction between experimental observations and theoretical predictions of the height of the barrier to O2 dissociation on Cu(1 0 0).