Adsorption and diffusion dynamics of atomic and molecular oxygen on reconstructed Cu(100)

Abstract

Adsorption dynamics of ${\mathrm{O}}_{2}$ on Cu(100) and on reconstructed $\mathrm{Cu}(100)\text{\ensuremath{-}}(2\sqrt{2}\ifmmode\times\else\texttimes\fi{}\sqrt{2})R45\ifmmode^\circ\else\textdegree\fi{}\text{\ensuremath{-}}\mathrm{O}$ at 300 and $553\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ have been investigated by employing a supersonic molecular-beam surface-scattering technique. Experimental results suggest that an activated direct adsorption channel is operative on the clean Cu(100), whereas the adsorption of ${\mathrm{O}}_{2}$ on the reconstructed Cu(100) is mediated either by a precursor state or by steering effects. First-principles molecular-dynamics simulations and potential-energy surface calculations show that the nature of the adsorption dynamics of ${\mathrm{O}}_{2}$ is different between the clean and reconstructed Cu(100) surfaces. The ${\mathrm{O}}_{2}$ molecule is likely to diffuse away from the reconstructed area or to completely desorb from the surface, while in the case of the clean Cu(100) surface, the adsorption occurs through a direct dissociative trajectory. We also find that in the case of the reconstructed surface, the steering occurs higher over the surface and that the recoil effect does not modify the surface as much as in the case of the clean surface. Moreover, the mobility of O and Cu adatoms on the reconstructed Cu surface is significantly lower than that on the clean surface both in the direction of the missing rows and in the direction perpendicular to them.