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  • Letter
  • Open Access

Ionization potential of radium monofluoride

S. G. Wilkins1,2,*, H. A. Perrett3,†, S. M. Udrescu1,‡, A. A. Kyuberis4,§, L. F. Pašteka4,5, M. Au2,6, I. Belošević1,7, R. Berger8, C. L. Binnersley3 et al.

M. L. Bissell3, A. Borschevsky4, A. A. Breier9, A. J. Brinson1, K. Chrysalidis2, T. E. Cocolios10, B. S. Cooper3, R. P. de Groote10, A. Dorne10, E. Eliav11, R. W. Field1, K. T. Flanagan12,3, S. Franchoo13, R. F. Garcia Ruiz1, K. Gaul8, S. Geldhof10, T. F. Giesen9, F. P. Gustafsson10, D. Hanstorp14, R. Heinke2, Á. Koszorús2, S. Kujanpää15, L. Lalanne10, G. Neyens10, M. Nichols14, J. R. Reilly3, C. M. Ricketts3, S. Rothe2, A. Sunaga16,17, B. van den Borne10, A. R. Vernon3, Q. Wang18, J. Wessolek3, F. Wienholtz2, X. F. Yang19, Y. Zhou20, and C. Zülch8

  • *Contact author: wilkinss@mit.edu
  • †Contact author: holly.perrett@manchester.ac.uk
  • ‡Contact author: sudrescu@mit.edu
  • §Contact author: a.kiuberis@rug.nl
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Phys. Rev. Research 8, L012012 – Published 13 January, 2026

DOI: https://doi.org/10.1103/fvsy-v1q6

Abstract

The ionization potential (IP) of radium monofluoride (RaF) was measured to be 4.969(2)[10] eV, revealing a relativistic enhancement in the series of alkaline earth monofluorides. The results are in agreement with a relativistic coupled-cluster prediction of 4.981(7) eV, incorporating up to quantum electrodynamics corrections. Using the same computational methodology, an improved calculation for the dissociation energy (D0) of 5.54(5) eV is presented. This confirms that RaF joins the group of diatomic molecules for which D0>IP, paving the way for precision control and interrogation of its Rydberg states.

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Phys. Rev. Research 8, L012012– Published 13 January, 2026
  • Received 16 October 2024
  • Revised 21 May 2025
  • Accepted 25 October 2025
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