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O: Oberflächenphysik
O 22: POSTER II
O 22.18: Poster
Wednesday, March 19, 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.