Image-potential resonances studied by selective electron scattering in thin Pb(1 1 1) films and clusters on Ge(1 1 1)

Image-potential resonance related peaks are observed in HREEL spectra by so-called selective electron scattering at the reciprocal lattice vector of a thin Pb(1 1 1) film. Upon a variation of the scattering conditions the spectral features change according to the electron scattering process and the effective masses, i.e. dispersion, of different orders are obtained. Image-potential resonances on the continuous film at 120 K and on lead islands at 300 K are equivalent. Electron scattering processes in the thin lead film can be distinguished from those in the substrate. In this way, the Stranski–Krastanov growth mode at room temperature is confirmed by separate electron scattering events on surface regions with different reciprocal lattice vectors. The appearance of an additional peak might be due to the presence of domain walls on the surface.