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Abstract

With the Penning-trap mass spectrometer Pentatrap it is possible to carry out mass ratio determinations with a relative uncertainty of a few times 10⁻¹². This is achieved by using a stack of five cylindrical Penning traps in a strong, homogeneous 7 T magnetic field, stabilized against environmental influences, which allows phase-sensitive detection methods on single highly charged ions. The core of this thesis are three peer-reviewed publications that present measurements with the mass spectrometer Pentatrap. The first and second publication present the determination of the atomic mass of lead-208 and uranium-238 to an unparalleled precision in the heavy mass sector of 7 and 6 × 10⁻¹¹, respectively. These results directly contribute to the mass “backbone”, a number of nuclides whose mass is known to high precision, allowing one to improve relative mass measurements in the range of heavy and superheavy nuclides as well as to determine the g-factor of the bound electron in heavy, hydrogenlike ions. In the third article, a metastable state with an excitation energy of around 31 eV was measured in ²⁰⁸Pb⁴¹⁺ as a mass difference on top of the absolute mass of the lead ion of ≈194 GeV/c² and compared to two ab initio multiconfiguration Dirac-Hartree-Fock atomic-structure calculations.