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要旨:
The charge state distribution of ions of a heavy nuclei species in the stellar plasma environment
in which they were formed by s-process nucleosynthesis is investigated. Our aim is to gain
insight about the atomic inner-shell electron occupation of heavy elements. The vacancy of
the inner shells are of interest when evaluating the role of electronic recombination processes like
nuclear excitation by electron capture in s-process nucleosynthesis. To this end we investigate the
ionization of osmium (Z=76) as a test case in stellar plasma conditions relevant for the formation
of heavy nuclei. For these parameters we derive the ionization states that are formed with the
help of the Saha equation. The potential generated by the plasma electrons and ions is treated
in the framework of the Fermi model including quantum mechanical corrections. The latter is
used to obtain the reduction of the atomic binding energies and the correction of the partition
functions due to the plasma particles. Our results predict free K and nearly free L shells for
osmium for various plasma parameter sets typical for the s-process sites. These _ndings support
the further study of nuclear excitation by electron capture in stellar plasmas, given that the
former is strongly facilitated when recombination in inner shells is possible.
