ELECTROCHEMICAL SURFACE ALLOYING OF SILVER ON PT(100) - LEED AND AUGER STUDY

Under potential deposition (UPD) of silver on Pt(100) exhibits two sharp peaks, each corresponding to the deposition of almost one monolayer; the first one is located 0.48 V above the Ag+/Ag equilibrium potential Eb for the bulk deposit, the second one just above this potential. After repeated Ag adsorption-desorption cycles, down to Eb new peaks can be observed between the two initial ones, which imply some modifications of the composition or structure of the surface. On the one hand, a study of the dependence of the amplitude of platinum and silver Auger lines on the polar angle of incidence of the primary electron beam gives evidence for surface alloying, when the electrode has been submitted to these repeated cycles. On the other hand, LEED examination of the surface emersed from the cell always exhibit the geometry of a primitive Pt(100) surface net, had it been subjected to silver adsorption-desorption cycles or not. © 1990.