Nuclei are the tiny, dense cores of atoms that contain protons and neutrons. Protons and neutrons have a property called spin, which can be thought of as the rotation of the particles around their own axes. In most nuclei, the spins of the protons and neutrons cancel each other out, resulting in a total nuclear spin of zero.
However, in certain nuclei, the spins of the protons and neutrons do not cancel out completely, resulting in a non-zero nuclear spin. This phenomenon is known as nuclear magnetic resonance (NMR), and it is the basis of a variety of important technologies, such as magnetic resonance imaging (MRI) and nuclear magnetic resonance spectroscopy (NMR spectroscopy).
For decades, scientists have been puzzled by an anomaly in the NMR spectra of certain nuclei. This anomaly, known as the "quenching of the magnetic dipole moment," occurs when the nuclear spin is reduced by the presence of an external magnetic field.
The Argonne-led team of scientists has now resolved this anomaly by showing that it is caused by the interaction between the nuclear spin and the electrons in the atom. This interaction, which is known as the hyperfine interaction, can cause the nuclear spin to be aligned with or against the external magnetic field, resulting in a reduction in the nuclear magnetic moment.
This finding could have implications for fundamental physics, as it provides new insights into the interactions between nuclei and electrons. It could also have practical applications, such as the development of new materials for quantum computers and other technologies.
"This is a significant breakthrough that has been decades in the making," said Argonne physicist and study co-author Samrat Sharma. "We are excited to finally understand the origin of this anomaly and explore its potential implications for science and technology."
The study was funded by the U.S. Department of Energy's Office of Science and the National Science Foundation.
