High-Resolution EPR Achieves 210 Ppb Resonance Width with 396GHz Excitation

Scientists have long sought to enhance the spectral resolution of electron paramagnetic resonance (EPR), a crucial technique in physics, biology and medicine. Colin J Stephen, Anton Tcholakov, and Maik Icker, all from the Department of Physics at the University of Warwick, alongside Stuart M Graham, Xiaoming Zhao, and Robert Day et al, have now overcome a significant hurdle in achieving this goal. Their work details a novel EPR spectrometer operating at a high magnetic field of 14 Tesla with 396GHz excitation, delivering exceptionally sharp resonances , boasting a full-width half-maximum of just 210 parts per billion. This breakthrough, adapting techniques from liquid-state nuclear magnetic resonance (NMR), allows for unprecedented precision in measuring resonance positions and g-factors, reaching an accuracy of 16 parts per billion and establishing a new standard for EPR spectroscopy.

High-Resolution EPR Spectroscopy at Terahertz Frequencies reveals novel

This advancement overcomes long-standing limitations in terahertz instrumentation, unlocking the full potential of high-field EPR for applications in physics, chemistry, biology, and medicine. Experiments demonstrate that resolving resonances becomes possible with this new level of spectral resolution, mirroring the indispensable role of high-resolution liquid-state NMR in analytical chemistry. Previous high-field EPR studies have occasionally combined NMR techniques, particularly for dynamic nuclear polarisation (DNP) investigations, but this work establishes a new standard for accuracy and precision. Indeed, a single trapped electron’s cyclotron resonance previously yielded a g-factor measurement of 2.002 319 304 361 70 (152), exceeding one part per trillion, however, EPR measurements have not approached this level of performance until now.

14T EPR with In-situ NMR Calibration provides high-resolution

Experiments employed a meticulously controlled environment to minimise external influences on the delicate measurements, ensuring the reliability of the obtained g-factor values. This measurement exemplifies the spectrometer’s capability to resolve subtle spectral features and quantify them with exceptional precision. This advanced EPR spectrometer delivers a substantial improvement over existing technology, enabling the study of materials with unprecedented detail. The combination of high magnetic field, high-frequency excitation, and in-situ NMR referencing represents a significant methodological innovation, paving the way for more accurate and sensitive EPR spectroscopy across diverse scientific disciplines. The approach enables the investigation of complex systems and the determination of fundamental physical constants with enhanced accuracy and reliability.,.

Subtle EPR Resolution Boosted by Liquid NMR

The uncertainties in the g-factors are limited by the quality of magnet shimming, but the achieved precision represents a substantial advancement in EPR spectroscopy. Data shows that the spectrometer can resolve spectral splitting in lithium metal particles within LiF, a phenomenon typically undetectable at lower magnetic fields, due to the particles’ varying shapes and sizes. The EPR of lithium metal particles in LiF was measured with a field sweep at 14 T, revealing multiple peaks attributable to variations in particle morphology, a detail lost at conventional EPR frequencies. Tests prove that the spectrometer’s high resolution can discern subtle differences in particle characteristics, opening new avenues for materials characterization.

High-Resolution EPR via NMR Referencing offers precise spectral

This advancement overcomes previous limitations imposed by the availability of suitable terahertz instrumentation, enabling more precise measurements of electron spin resonances. This innovative approach significantly enhances the reliability of g-factor determinations. The authors acknowledge that the current setup is limited to liquid samples, restricting its application to certain materials. Future work could focus on adapting the techniques to solid-state samples, broadening the scope of this high-resolution EPR spectroscopy. Further refinement of the instrumentation and exploration of different endohedral fullerenes are also potential avenues for research, promising even greater precision and insight into the properties of these fascinating systems.