A CORE-LEVEL PHOTOEMISSION SPECTROSCOPY STUDY OF THE FORMATION OF SURFACE ALLOY CU PT(111) - COMPARISON WITH PT/CU(111)/

We present first results on the formation of a surface alloy starting from the deposition of thin Cu films on a Pt(111) substrate. Annealing at 300 degrees C leads to the kinetic blocking of the dissolution pro cess. We have used synchrotron radiation to measure the Pt4f(7/2) core -level shifts due to the alloying process. We estimate the Pt concentr ation in the surface layer to be 50%. These results are compared to pr evious work on the Pt/Cu(111) system which demonstrated the formation of a Cu3Pt surface alloy. The influence of surface segregation and bul k alloying in driving the formation of a surface-alloy phase during di ssolution is discussed.