Are Barrier Films That Protect the Metal against Oxidation by Airr

Self-assembled monolayers (SAMs) derived from adsorption of n-alkanethiols onto the surfaces of copper slow the oxidation of the copper surface by ieaction with atmospheric dioxygen. Angstrom-lervel changes in the thickness of the monolayer result in readily observable differences (by X-ray pirotoelectron spectroscopy, XPS) in the rates of oxidation of the copper and adsorbed thiolates. The rates of oxidation oittre copper and fhe thiolates can be decreased by -50Vo by increasing the length of the adsorbate, and thus of the SAM, by foui CH, units. Ttre species present on lle. oxidized interface-both alkanesulfonate and Cu(lI)-are replaced when the-assemblage is exposed to solutions of alkanethiols, and the resulting SAMs resembled those that were present before the oxidation, although the supporting surface is rougher.