Core level electron energy loss study of the PD-SI(111)2 × 1 Interface Formation

The structural and surface sensitivity of electron energy loss spectroscopy has been exploited to investigate the Pd-Si(lll)2 × 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 ÷ 20) Å and the presence of a peculiar Pd-Si compound at coverages lower than 5 Å was obtained.