University of Jyväskylä part of breakthrough: Nuclear magnetism measured in a new way
The University of Jyväskylä has been part of an international research team at the ISOLDE facility at CERN, which has achieved a significant breakthrough in nuclear and molecular physics.
Radium fluoride revealed the hidden interaction of electrons
The observation was made possible by the short-lived radioactive molecule radium monofluoride (225Ra19F). The pear-shaped nucleus of radium makes it extremely sensitive to nuclear forces and particle physics phenomena. Using high-resolution laser spectroscopy, the researchers were able to observe, for example, the Bohr–Weisskopf effect, where the molecule’s energy levels shift slightly due to the internal magnetic structure of the nucleus.
“This phenomenon has not previously been observed in molecules, and there is now evidence that molecules can serve as highly useful tools for investigating nuclear structure,” explains researcher Sonja Kujanpää, who was working at JYU while conducting the research.
The experiment was carried out at ISOLDE by producing radium fluoride molecules in nuclear reactions, and the nuclear structure of the produced radioactive molecules was measured using lasers. The measurements were combined with advanced quantum-chemical calculations, which reduced the deviation between theoretical and experimental results to less than one percent, also reflecting the rapid development of computational molecular physics. In this way, the researchers were able to determine the energy levels of the RaF molecules with very high precision.
Breakthrough could transform fundamental research in physics
Heavy radioactive molecules like 225Ra19F can help explain why the Universe consists mainly of matter rather than antimatter, reveal new mechanisms of CP symmetry violation that are not explained by current particle physics models, refine theories of nuclear forces, and provide information about the properties of matter similar to that in neutron stars.
New methods and molecules take precision measurements to the next level
The results provide a basis for future experiments that can achieve extremely high precision.
“We have only just begun to understand what these new studies may reveal,” says Kujanpää. “At present, several research teams worldwide are developing both experimental and theoretical methods to utilise molecules like the radium fluoride. Even more precise experimental developments can be built on the foundation laid by this work.”
The research article was published in the Science publication series on 23 October 2025.
Article information:
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Observation of the distribution of nuclear magnetization in a molecule, Science, 23.10.2025
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Link to the article: https://www.science.org/doi/10.1126/science.adm7717
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Doi 10.1126/science.adm7717
Further information:
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Researcher Sonja Kujanpää, sonja.kujanpaa@epfl.ch
