R. Fischer et T. Fauster, ALLOYING OF THIN AG AND AU FILMS ON PD(111) STUDIED BY HIGH-RESOLUTION PHOTOELECTRON-SPECTROSCOPY OF SURFACE-STATES, Surface review and letters, 3(5-6), 1996, pp. 1783-1789
Alloy formation by annealing of thin Ag and Au films on Pd(111) is stu
died by high-resolution ultraviolet and two-photon photoelectron spect
roscopy of surface states. Changes in the composition of the top layer
of the surface alloys are reflected in the energy of the surface stat
es. Above an annealing temperature of 500 K on both systems, the cryst
al-induced surface state shifts continuously from the occupied state o
f the adsorbate to the unoccupied state of the substrate. The continuo
us shift reflects the variable composition of the alloys in the surfac
e region which depends on the initial coverage and the annealing tempe
rature. The spectroscopy of the unoccupied image states permits the in
vestigation of growth and morphology of deposited metal layers. Three-
dimensional island growth, layer-by-layer growth, and surface alloy fo
rmation with metastable surface configurations and diffusion of the ov
erlayer material into the bulk are identified.