- MIT physicists probed atomic nuclei using molecules instead of a particle accelerator.
- Electrons briefly enter the radium nucleus and return with a measurable energy shift.
- The detected shift was one millionth the energy of the excitation laser photon.
Most experiments that peer inside an atomic nucleus require kilometers-long particle accelerators. MIT physicists just did it on a tabletop - by tricking electrons into becoming "nuclear spies" reporting from inside atomic nuclei.
As reported in Science, physicist Ronald Fernando Garcia Ruiz and his team at MIT developed a method that uses molecules as microscopic particle colliders. They paired radioactive radium atoms with fluoride atoms, creating radium monofluoride molecules.
Inside these molecules, the electric fields squeeze electrons so tightly that they briefly penetrate the radium nucleus. They then emerge carrying information about what they encountered inside.
Key figure
1 / 1,000,000
The energy shift detected – one millionth the energy of the laser photon used to excite the molecules
Why trap electrons in molecules
The insight is elegant. When you confine a radium atom inside a molecule, the internal electric field becomes orders of magnitude stronger than anything physicists can generate in a lab.
"In a way, the molecule acts like a giant particle collider," explains study co-author Silviu-Marian Udrescu.
This molecular trap effectively amplifies electron behavior. The electrons ping around with enough energy to briefly penetrate the nucleus and interact with its protons and neutrons.
When they zip back out, they carry a telltale energy shift.
Detecting a nuclear whisper
The challenge was measuring that shift. Lead author Shane Wilkins and colleagues cooled the molecules, sent them through vacuum chambers, and bombarded them with lasers to measure electron energies with extreme precision.
The energy shift they detected was vanishingly small, measuring just one millionth the energy of the laser photon used to excite the molecules. But it was there.
A signal small enough to doubt, but too real to ignore.
The electrons showed slightly different energies than expected, proving they'd interacted with the nucleus from the inside.
"There are many experiments measuring interactions between nuclei and electrons outside the nucleus," Wilkins notes. "When we went to measure these electron energies very precisely, it didn't quite add up."
When we went to measure these electron energies very precisely, it didn't quite add up.
Shane Wilkins, Paper Co-author
Do atomic nuclei answer cosmic puzzle?
The technique offers a new way to map the magnetic distribution inside atomic nuclei, showing how protons and neutrons align as tiny magnets based on their spatial arrangement. For radium, whose pear-shaped nucleus could amplify violations of fundamental symmetries, this matters enormously.
What is nuclear magnetization distribution?
Every proton and neutron inside a nucleus behaves like a tiny magnet, spinning on its own axis. How these particles are arranged and oriented determines the overall magnetic character of the nucleus. The “magnetization distribution” is the map of where that magnetic influence is strongest inside the nucleus – information that was essentially inaccessible before techniques like this one.
Those symmetry violations might explain one of cosmology's deepest puzzles: why the universe contains so much matter and almost no antimatter, despite predictions that both should have been created in equal amounts after the Big Bang.
Garcia Ruiz's team now plans to cool these molecules further and control their nuclear orientations. The goal: hunt for symmetry violations that current physics can't explain.
"We now have proof that we can sample inside the nucleus," Garcia Ruiz says. "It's like being able to measure inside a battery–far more challenging than measuring its external field."
Sources
- Primary Research: Wilkins, S. G., Udrescu, S. M., Athanasakis-Kaklamanakis, M., Garcia Ruiz, R. F., Belosevic, I. et al. 2025. "Observation of the distribution of nuclear magnetization in a molecule." Science. (MIT Open Access article)
- Additional context:
- With a new molecule-based method, physicists peer inside an atom’s nucleus
(Jennifer Chu, MIT News, October 23, 2025)
- With a new molecule-based method, physicists peer inside an atom’s nucleus
Fact Check: Claim-by-Claim Verification Verified
All claims verified against the Science paper (DOI:10.1126/science.adm7717) and MIT News press release. Quotes, measurements, and scientific context confirmed.
Commentary
- The "tabletop" framing comes from MIT News. The actual experiments were conducted at CERN's ISOLDE facility, not at MIT. The method itself is tabletop-scale compared to a particle accelerator.
- "Particle collider" is metaphorical; the technique uses laser spectroscopy.
- Matter-antimatter connection is theoretical motivation, not a proven explanation.
Sources used for verification
Academic/Peer-reviewed:
Other reliable sources:
Fact-checked by Perplexity Sonar Pro on 2026-03-15
