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Q: Fachverband Quantenoptik und Photonik
Q 38: Precision Spectroscopy of Atoms and Ions III (joint session A/Q)
Q 38.1: Invited Talk
Wednesday, March 4, 2026, 14:30–15:00, N 3
Enhanced Sensitivity for Electron Affinity Measurements — •Franziska Maria Maier, Erich Leistenschneider, Lutz Schweikhard, and Stephan Malbrunot-Ettenauer — CERN
The electron affinity (EA) reflects the energy released when an electron is attached to a neutral atom and encodes key information about atomic structure, electron correlation effects and chemical reactivity. However, the EA of the heaviest elements of the periodic table remain experimentally unexplored despite their fundamental importance to benchmark atomic many-body calculations with implications across atomic and nuclear physics, quantum chemistry and radiopharmaceutical research. We have developed a novel technique to determine EAs through Laser Photodetachment Threshold Spectroscopy, performed in an electrostatic ion beam trap, a so called MR-ToF device [1]. Our method increases the sample’s exposure to laser photons and, thus, enhances the experimental sensitivity by three orders of magnitude. By applying this technique, we measured the EA of 35Cl to be 3.612720(44) eV, achieving state-of-the-art precision while employing five orders of magnitude fewer anions. This unprecedented sensitivity paves the way for systematic EA measurements across isotopic chains - including isotope shifts and hyperfine splittings - and ultimately for the first direct determination of electron affinities in superheavy elements. This presentation will introduce our novel method and present our experimental results. [1] F. M. Maier, E. Leistenschneider et al., Nat. Commun. 16, 9576 (2025).
Keywords: MR-ToF; ion traps; electron affinity; superheavy elements; radioactive isotopes