SAMOP 2023 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 55: Precision Spectroscopy of Atoms and Ions III (joint session A/Q)
Q 55.6: Vortrag
Donnerstag, 9. März 2023, 16:00–16:15, F303
Hyperfine structures of neptunium — •Magdalena Kaja1, Mitzi Urquiza-González2, Felix Berg1, Korbinian Hens2, Tobias Reich1, Matou Stemmler1, Dominik Studer1, Felix Weber1, and Klaus Wendt1 — 1Johannes Gutenberg University, 55099 Mainz — 2Hübner GmbH & Co. KG, Kassel, Germany
Neptunium is of major concern for the long-term safety of a high-level nuclear waste repository due to the long half-life of 2.1·106 years and the high radiotoxicity of its isotope 237Np. In this context, trace analysis of environmental samples is of high relevance. Resonance ionization mass spectrometry (RIMS) is an excellent tool for selective and sensitive ultra-trace analysis of radionuclides but requires efficient excitation schemes and a suitable tracer for quantification. For isotope ratio determination, it is important to take into account the isotope-related effects in ionization schemes stemming from hyperfine structure (HFS) and isotope shift. Thus, new two-step excitation schemes for analysis of 237Np and 239Np as a tracer were identified and investigated.
Narrow bandwidth spectroscopy on 237Np and 239Np has been carried out at RISIKO mass separator using the specific PI-LIST laser ion source geometry together with an injection-locked seeded Ti:sa laser system. The latter has a spectral bandwidth of 20 MHz, while also providing a high repetition rate pulsed operation with the high-power density required for RIS. The HFS of the atomic ground-state transitions to the levels at 25 075.15 cm−1 and 25 277.63 cm−1 has been measured and hyperfine coupling constants for both isotopes as well as the isotope shift between 237Np and 239Np have been determined.