Fast, broad-band magnetic resonance spectroscopy with diamond widefield relaxometry

TL;DR

This paper introduces a rapid, broad-band magnetic resonance spectroscopy method using diamond NV centers that is compact, fast, and sensitive, enabling full spectrum acquisition in seconds without bulky equipment.

Contribution

The authors develop a diamond-based EPR spectroscopy technique that significantly reduces measurement time and equipment size while maintaining high sensitivity.

Findings

Full spectrum reconstructed in 3 seconds over 3-11 Gauss range

Detected 1 μM copper ion solution with only 0.5 μL volume

Achieved 12-minute data acquisition reduced to seconds

Abstract

We present an alternative to conventional Electron Paramagnetic Resonance (EPR) spectroscopy equipment. Avoiding the use of bulky magnets and magnetron equipment, we use the photoluminescence of an ensemble of Nitrogen-Vacancy centers at the surface of a diamond. Monitoring their relaxation time (or T1), we detected their cross-relaxation with a compound of interest. In addition, the EPR spectra are encoded through a localized magnetic field gradient. While recording previous data took 12 minutes per data point with individual NV centers, we were able to reconstruct a full spectrum at once in $3\; \textrm{seconds}$, over a range from $3$ to $11\; \textrm{Gauss}$. In terms of sensitivity, only $0.5\; {\mu}\textrm{L}$ of a $1\; {\mu}\textrm{M}$ hexaaquacopper (II) ion solution was necessary.