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Research group Z. Harman – Division C. H. Keitel
Abstract:
In this thesis, quantum electrodynamic (QED) effects in few-electron highly charged ions
are investigated. The interaction of the electron with the nucleus is taken into account in a
nonperturbative manner. A versatile approach to accurately calculate self-energy corrections
combining finite basis sets with analytical methods is presented. The approach is applicable
to many-electron ions using the screening-potential approximation. The method is applied
to calculate self-energy corrections to the energy level of the electron in the 4d3/2 state
of 131Xe17+ and to the excitation energy of the 4d -> 4f excitation in 187Re29+. QED
corrections to the g factor of lithiumlike and boronlike ions in a wide range of nuclear charges
are presented. Many-electron contributions as well as radiative effects on the one-loop level
are calculated. Contributions resulting from the interelectronic interaction, derived in a
QED framework, and most of the terms of the vacuum polarization effect are evaluated
to all orders in the nuclear coupling strength Zα. Uncertainties resulting from nuclear
size effects, numerical calculations, and uncalculated effects are discussed. Finally, a new
approach to determine the fine-structure constant α using a weighted difference of the bound electron
g factor and energy in hydrogenlike systems is put forward. It is shown that nuclear
structural effects are sufficiently well suppressed while sensitivity to α is enhanced in this
weighted difference, as compared to the g factor.
