engleski

Electronic excitations in thin metallic films

Confinement of valence electrons in metallic films of thickness comparable with the electron Fermi wavelength results in discrete quantum well states, which are the origin of quantum size effects in the properties of the system. Most theoretical studies have focused on the electronic structure of these systems and less attention has been paid to study of the electronic excitations. In present contribution we perform investigation of the evolution of the electronic excitations in thin Ag(111) films as a function of thickness considering its electronic band structure on a more realistic basis in comparison with the jellium model. For this we employ a model potential. This potential mimics the atomic structure of the Ag(111) in the direction z perpendicular to the surface, and correctly reproduces the experimental Ag(111) work function, the projected bulk band structure, the surface and first image-potential states. With the use of this model potential we have performed self-consistent calculations of the surface response function of the Ag slabs of 1-10 monolayer thickness. For comparison, we also performed similar calculations using the energy band structure obtained whitin a conventional jellium model. The comparison of these two sets of data reveals striking differences in the excitation spectra of Ag films. The origin of these differences resides in the different band structures of two models.

Acoustic surface plasmon; Quantum size effect

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