ANGLE-RESOLVED PHOTOEMISSION FROM AU DEPOSITED ON AG(111) - EVIDENCE FOR SURFACE ALLOY FORMATION

We have performed an extensive study of angle-resolved normal photoemi ssion from Au deposited on Ag(111) at temperatures T less-than-or-equa l-to 330 K. In contrast to other authors we do not observe a layer-by- layer growth of Au(111) with an abrupt interface to the substrate. Our results present clear evidence that in the first deposition steps on ordered alloy interface develops, with a silver-rich outermost layer a nd an estimated thickness of at least 4-5 monolayers, until after more than 5 nominal Au-monolayers bulk-like gold starts to grow. Besides i nformation on the particular Au/Ag(111) system our results demonstrate the capabilities of angle-resolved photoemission to explore extended interfaces.