Researchers at NIST have developed a new type of microresonator that can detect electron paramagnetic resonance (EPR) signals from extremely small samples, down to picoliter volumes. These microresonators are fabricated using standard photolithographic techniques and can be integrated into existing EPR spectrometers.
The key advantage of these microresonators is their ability to detect EPR signals from samples that are too small for conventional EPR techniques, which typically require microliter volumes. This opens up new possibilities for studying nanoscale materials, such as thin films and interfaces, as well as biological samples like biomacromolecules and polymers.
The microresonators work by confining the microwave excitation field to a sub-wavelength scale around the central bridge of the resonator structure, which helps to minimize radiative losses and improve sensitivity. The planar inverse anapole resonator design is particularly effective at reducing far-field radiative losses, leading to a significant increase in sensitivity compared to conventional cavity resonators.
The NIST team has successfully demonstrated the use of these microresonators in both 9 GHz and 34 GHz EPR spectrometers, and the technology has potential applications in solid-state physics, materials science, and structural biology. The next steps will involve further optimization of the resonator design and integration with other EPR techniques to expand the range of samples that can be studied.
Keywords: 1. Microresonators, 2. Electron Paramagnetic Resonance (EPR), 3. Sensitivity, 4. Volume-Limited, 5. Nanoscale Dimensions
