Scientists in Germany have uncovered previously unknown properties of the rare Earth element samarium by developing a powerful new technique to investigate the internal structure of atoms.
For the discovery, the research team at the Johannes Gutenberg University Mainz (JGU) and the Helmholtz Institute Mainz (HIM) applied an advanced laser-based technique known as dual-comb spectroscopy (DCS).
The method, which enabled them to measure atomic spectra at a wide band of electromagnetic frequencies with high resolution and sensitivity, helped the team uncover hidden atomic transitions in the rare element.
Samarium (Sm) is critical for producing high-performance samarium-cobalt (SmCo) permanent magnets used in electric vehicle motors and wind turbine generators.
The findings also helped pave the way for ‘Spectroscopy 2.0,’ a next-generation platform designed as a ‘massively parallel spectroscopic tool’ capable of simultaneously performing many measurements.
Breaking the limits
Comprehending the internal structure of atoms is crucial to understanding the composition of matter and designing new experiments to explore fundamental physics. However, the energy-level structures of many atoms are still not fully explored, especially in the case of rare earths and actinides.
Spectroscopy, which is based on the principle that electrons absorb or emit energy when they move between energy levels in an atom, is one of the most widely used methods for studying an atom’s structure.
“High-resolution broadband spectroscopy is essential for precision measurements in atomic physics and the search for new fundamental interactions,” Razmik Aramyan, PhD student at the University of the study’s main author, explained.
Credit: Razmik Aramyan
Nevertheless, according to the PhD student, progress is often hindered by the challenge of measuring complex atomic spectra, as it is difficult to properly distinguish the sample’s signals and the limited range of wavelengths that instruments can detect.
To overcome the challenges, Aramyan and his team utilized a method known as dual-comb spectroscopy (DCS), which is based on the 2005 Nobel-winning optical frequency comb technique.
This method, where two synchronized comb lasers measure light frequencies with greater accuracy than conventional methods, allowed them to measure atomic spectra at a wide band of electromagnetic frequencies with high resolution and high sensitivity.
Unlocking atomic secrets
To detect weak signals with high precision, the team implemented multiple photodetectors to improve the signal-to-noise ratio. This made it possible to clearly identify the experimental data and determine the spectrum’s wavelengths.
“This study introduces an enhanced multichannel DCS approach that combines a photodetector array with a novel scheme for resolving frequency ambiguities, enabling ambiguity-free, high-signal-to-noise-ratio broadband measurements,” Aramyan stated.
The researchers described this as the first step toward ‘Spectroscopy 2.0’, a tool that will be used to perform spectroscopy of dense atomic and molecular spectra under intense magnetic fields.
Since DCS is particularly well-suited to filling gaps in atomic data, the researchers recorded the spectrum of samarium vapor at different temperatures. They analyzed the spectral behavior at different samarium concentrations.
When comparing the results, they were stunned to discover several previously undescribed samarium absorption lines. “This illustrates the potential of our method to uncover previously unknown atomic properties,” Aramyan said in a press release.
According to the team, the findings open promising possibilities for massively parallel spectroscopy, including studies of atoms in pulsed, ultra-high magnetic fields.
The study has been published in the journal Physical Review Applied.