Role of steps and of terrace width in gas-surface interaction:: O2/Ag(410) -: art. no. 276101

We demonstrate by vibrational spectroscopy that open steps are the active site for O-2 dissociation on Ag(410), and that the barrier to adsorption at defects can be measured by energy and angle resolved investigation of the dynamics of the gas-surface interaction. We identify a molecular adsorption channel with considerably reduced activation barrier and a nonactivated dissociative pathway. The O-2 sticking probability is increased at steps and strongly reduced at terraces with respect to Ag(100), implying that reactivity is influenced by terrace width.