2025/03/04 by Janis Smits, Smits, Janis, Yaser Silani +17 · 1 voice · 1 citation
Physics and Astronomy · #Applied Physics (physics.app-ph) #Chemical Physics (physics.chem-ph) #FOS: Physical sciences #Instrumentation and Detectors (physics.ins-det) #Optics (physics.optics) #Quantum Physics (quant-ph) #physics.app-ph #physics.chem-ph #physics.ins-det #physics.optics #quant-ph
paper · pdf · doi:10.48550/arxiv.2503.02140
Non-inductive magnetometers based on solid-state spins offer a promising solution for small-volume nuclear magnetic resonance (NMR) detection. A remaining challenge is to operate at a sufficiently high magnetic field to resolve chemical shifts at the part-per-billion level. Here, we demonstrate a Ramsey-Mz protocol that uses Ramsey interferometry to convert an analyte's transverse spin precession into a longitudinal magnetization (Mz), which is subsequently modulated and detected with a diamond magnetometer. We record NMR spectra at B0=0.32 T with a fractional spectral resolution of ~350 ppb, limited by the stability of the electromagnet bias field. We perform NMR spectroscopy on a ~1 nL detection volume of ethanol and resolve the chemical shift structure with negligible distortion. Through simulation, we show that the protocol can be extended to fields up to B0=3 T, with minimal spectral distortion, using composite nuclear-spin inversion pulses. For sub-nanoliter analyte volumes, we estimate a resolution of ~1 ppb and concentration sensitivity of ~40 mM s1/2 is feasible with improvements to the sensor design. Our results establish diamond magnetometers as high-resolution NMR detectors in the moderate magnetic field regime, with potential applications in metabolomics and pharmaceutical research.