Fast, Broad-Band Magnetic Resonance Spectroscopy with Diamond Widefield Relaxometry

Area of Science:

• Quantum Sensing
• Spectroscopy
• Materials Science

Background:

• Conventional Electron Paramagnetic Resonance (EPR) spectroscopy relies on bulky and expensive equipment, including large magnets and magnetrons.
• Existing EPR methods can be time-consuming, with data acquisition taking minutes per data point.
• There is a need for more portable, sensitive, and rapid EPR techniques for various applications.

Purpose of the Study:

• To present an alternative, more efficient EPR spectroscopy technique.
• To demonstrate the use of diamond nitrogen-vacancy (NV) centers for EPR measurements.
• To improve the speed and sensitivity of EPR spectral acquisition.

Main Methods:

• Utilized the photoluminescence of ensemble nitrogen-vacancy (NV) centers on a diamond surface.
• Monitored the relaxation time (T1) of NV centers to detect cross-relaxation with target compounds.
• Encoded EPR spectra using a localized magnetic field gradient for rapid data reconstruction.

Main Results:

• Achieved a full EPR spectrum reconstruction in 3 seconds, a significant improvement over the previous 12 minutes per data point.
• Demonstrated successful detection of cross-relaxation with a compound of interest (hexaaquacopper(II) ion).
• Showcased high sensitivity, requiring only 0.5 μL of a 1 μM solution.

Conclusions:

• The developed NV-center-based photoluminescence method offers a viable and advanced alternative to conventional EPR spectroscopy.
• This approach provides a substantial increase in speed and maintains high sensitivity for compound detection.
• The technique holds promise for portable and rapid spectroscopic analysis in various scientific fields.