radio-frequency spectroscopy

Radio-frequency spectroscopy is a technique used to study the energy states of atoms, ions, and molecules. It focuses on magnetic interactions within these particles, which cause subtle differences in energy levels. These energy differences, typically ranging from 10⁶ to 10¹¹ hertz, are probed using radio waves or microwaves.12

This method was pioneered in the late 1930s by Isidor Rabi and his collaborators, who used molecular beams to measure absorption spectra. A significant advancement was the 1947 experiment by Willis Lamb and Robert Retherford, which measured the energy difference between two levels in hydrogen, leading to the concept of the Lamb shift and contributing to the development of quantum electrodynamics.1

Radio-frequency spectroscopy is highly sensitive and can detect single atoms or isotopes. It has found applications in various fields, including medical imaging (MRI) and astronomy, where it helps analyze the composition of distant stars and interstellar clouds.3