SURFACE-COMPOSITION OF CLEAN AND OXYGEN-COVERED AU3CU ALLOY

Surface segregation behavior of clean and oxygen-adsorbed Au3Cu system s has been studied theoretically within the tight-binding formalism. I t has been found that for the clean Au3Cu system the top layer is Au e nriched, while the second layer is Cu enriched. In the presence of a m onolayer of oxygen atoms, on the other hand, there is a segregation re versal in the top layer which becomes Cu enriched. The above findings are in total agreement with the very recent experimental impact collis ion ion-scattering spectroscopic results.