${}^{13}$C Hyperpolarization with Nitrogen-Vacancy Centers in Micro- and Nanodiamonds for Sensitive Magnetic Resonance Applications

Abstract

Nuclear hyperpolarization is a known method to enhance the signal in nuclear magnetic resonance (NMR) by orders of magnitude. The present work addresses the ${}^{13}$C hyperpolarization in diamond micro- and nanoparticles, using the optically-pumped nitrogen-vacancy center (NV) to polarize ${}^{13}$C spins at room temperature. Consequences of the small particle size are mitigated by using a combination of surface treatment improving the ${}^{13}$C relaxation ($T_1$) time, as well as that of NV, and applying a technique for NV illumination based on a microphotonic structure. Monitoring the light-induced redistribution of the NV spin state populations with electron paramagnetic resonance, a strong polarization enhancement for the NV spin state is observed in a narrow spectral region corresponding to about 4\% of these defect centers. By combining adjustments to the `PulsePol' sequence and slow sample rotation, the NV-${}^{13}$C polarization transfer rate is improved further. The hyperpolarized ${}^{13}$C NMR signal is observed in particles of 2 $\mu$m and 100 nm median sizes, with enhancements over the thermal signal (at 0.29 T magnetic field), of 1500 and 940, respectively. The present demonstration of room-temperature hyperpolarization anticipates the development of agents based on nanoparticles for sensitive magnetic resonance applications.

49 pages, 29 figures (main text: 15 pages, 5 figures and Supporting Information: 34 pages, 24 figures) Uploaded new version on March 24th, 2024: corrected affiliations, some typos/formatting

References in corpus (8)

• Recent developments in MAS DNP-NMR of materials
• State-selective intersystem crossing in nitrogen-vacancy centers
• Long Spin Coherence Times of Nitrogen Vacancy Centres in Milled Nanodiamonds
• Robust techniques for polarization and detection of nuclear spin ensembles
• Efficient Conversion of Nitrogen to Nitrogen-Vacancy Centers in Diamond Particles with High-Temperature Electron Irradiation
• Dynamic Nuclear Polarization in Battery Materials
• Large Room Temperature Bulk DNP of ${}^{13}$C via P1 Centers in Diamond
• Investigation of Near-Surface Defects of Nanodiamonds by High-Frequency EPR and DFT Calculation

Cited by in corpus (4)

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