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O: Oberflächenphysik

O 22: POSTER II

O 22.18: Poster

Mittwoch, 19. März 1997, 14:15–15:45, AULA

Influence of shallow core-levels on the plasmon properties of Zn — •K. Widder, M. Knupfer, O. Knauff, and J. Fink — Institut für Festkörper- und Werkstofforschung Dresden, Postfach 270016, D-01171 Dresden

The dielectric properties of the post transition metals is strongly influenced by the presence of shallow core-levels with excitation energies comparable to the plasmon energy. In most of these cases the excitation energies are slightly higher than the plasmon energy, which leads to a significant redshift of the latter.
One exception from this behaviour is Zn, where the core-level excitation energies are just below the plasmon energy, leading to a completely different behaviour of the free charge carrier plasmon properties. We present experimenatal results of an Electron Energy Loss Study. It has been found that the dispersion starts with negative values and the FWHM decreases with increasing momentum transfers.
This unusual behaviour can be explained within the framework of a Drude-Lorentz approach, when taking into account the strong decrease of the core-level excitation oscillator strength with increasing momentum transfers.