A CORE LEVEL ELECTRON-ENERGY LOSS STUDY OF THE PD-SI(111)2X1 INTERFACE FORMATION

The structural and surface sensitivity of electron energy loss spectroscopy has been exploited to investigate the Pd-Si(111)2 x 1 interface. We found the two M(IV), V shallow edges of Pd suitable for an EELS study on the whole coverage range. EXAFSlike oscillations were detectable above the M(IV), V edge for about 150 eV. These features together with the intensity ratio (M(V)/M(IV)) between the M(V) and M(IV) components showed a reproducible dependence vs. the thickness of the Pd film. From the analysis of the near edge part and the EXAFSlike oscillations a general indication of the formation of a compound very close to Pd2Si in the coverage range (5 divided-by 20) angstrom and the presence of a peculiar Pd-Si compound at coverages lower than 5 angstrom was obtained.