Dissociative Adsorption of Oxygen on Clean Cu(001) Surface

The initial stage of molecular oxygen adsorption on Cu(001) surface is investigated by scanning tunneling microscopy and first principles calculations. The molecule always dissociates on the surface between 5 and 300 K. The dissociated oxygen atoms adsorb at the two 4-fold hollow sites separated by twice of the nearest-neighbor distance of the surface Cu atoms in the close-packed directions, [110] and [110]. This is the most stable structure evaluated for the pair adsorbed at hollow site by the calculation. The adsorbed oxygen atoms stay at the same site below 80 K, and thermally migrate on the surface above 300 K.