ATOMIC-SCALE STUDIES OF CORROSION AND COR ROSION INHIBITION

High-resolution, in-situ scanning tunneling microscopy studies of the surface structure and the microscopic mechanisms of the dissolution of Cu(100) in hydrochloric and sulfuric acid solutions at low dissolutio n rates are presented. On clean Cu surfaces dissolution proceeds exclu sively at surface defects in form of atomic steps and is strongly depe ndent on the anion species. Foreign metal impurities can either inhibi t Cu dissolution via pinning or enhance it by inducing the formation o f etch pits. In the presence of inhibiting, organic adlayers the remov al of Cu atoms at the steps is significantly slower and corrosion is d etermined by the formation of etch pits at higher potentials.