Erlangen 2022 – scientific programme
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A: Fachverband Atomphysik
A 19: Precision spectroscopy of atoms and ions II (joint session A/Q)
A 19.5: Talk
Wednesday, March 16, 2022, 15:00–15:15, A-H2
Laser spectroscopy of neptunium - excitation schemes, atomic structure and the ionization potential — •Magdalena Kaja, Dominik Studer, Felix Weber, Felix Berg, Nina Kneip, Tobias Reich, and Klaus Wendt — Johannes Gutenberg University, 55099 Mainz
Neptunium is a radioactive actinide and the first transuranic element. In particular, 237Np is generated quantitatively within the nuclear fuel cycle with amounts on average ∼10 kg in each conventional pressurized water reactor each year. Due to its long half-live of 2.1·106 years and high radiotoxicity, it represents a major hazard in the final disposal of nuclear waste. Under environmental conditions, Np can be present in oxidation states +III to +VI and can form soluble species. In this context trace analysis of environmental samples is of high relevance. The development of efficient and selective laser ionization schemes plays an important role for Np spectroscopy and trace analysis.
The spectrum of Np has been studied at the Mainz Atomic Beam Unit, using widely tunable frequency-doubled Ti:Sapphire lasers. The ionization scheme development, spectra above and below the ionization potential (IP), as well as the electric field ionization technique, which allows the determination of the IP, are presented in this contribution. Narrow-band spectroscopy is planned to determine hyperfine structures and isotope shift. So far, only 237Np has been studied by laser spectroscopy and only in broad-band mode. Therefore, high-resolution spectroscopy is planned on 237Np and possibly on the short-lived isotope 239Np.