Pushing the limits of resonance ionization mass spectrometry - ionization efficiency in palladium and spectral resolution in technetium
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Abstract
Resonance ionization mass spectrometry is a versatile technique for highly selective ionization and optical spectroscopy. It uses stepwise, resonant excitation and subsequent ionization of atoms via powerful, precisely tuned laser radiation, followed by conventional mass spectrometry. As the method offers high isotope selectivity, it is used at on-line facilities worldwide to produce highly pure ion beams for the investigation of atomic and nuclear properties of the most exotic nuclei.
This thesis presents advancements on two key aspects of the method: ionization efficiency and spectral resolution. In the first part of this thesis, new highly efficient excitation ladders for palladium are developed, to facilitate high-precision measurements on neutron-rich radioisotopes. Measurements at two different mass separator setups yield excellent efficiencies well above 50 % which are the highest efficiencies presently reported for laser ion sources.
The second part of this thesis presents the development of a new laser prototype and a special laser ion source, which enable precise spectroscopy with highest spectral resolution. Both instruments are used for high-resolution hyperfine structure spectroscopy in radioactive Tc-97,98,99 using small samples of down to 10^11 atoms. The detailed analysis of the highly resolved spectra allows the precise determination of nuclear moments and other parameters.