Dielectric response of covered metal surfaces: Oxidation of Al(111) - art.no. 125410

We have studied the response of an Al(111) surface at different stages of t he oxidation process using a simple model for the dielectric response of th e covered metal surface. Our model includes the metal response and the pola rizability of the adsorbed oxygen atoms or oxide molecules depending on cov erage. The experimentally measured surface plasmon energy shift to lower en ergies as the coverage increases is reproduced by our model and is consiste nt with STM observations that interpret the Al oxidation in two steps: firs t O atoms are adsorbed (up to coverages of the order of 0.5 monolayers) and then oxidation starts to take place.