<sup>13</sup> C hyperpolarization with nitrogen-vacancy centers in micro- and nanodiamonds for sensitive magnetic resonance applications
Rémi Blinder, Yuliya Mindarava, Martin C. Korzeczek, Alastair Marshall, Felix Glöckler, Steffen Nothelfer, Alwin Kienle, Christian Laube, Wolfgang Knolle, Christian Jentgens, Martin B. Plenio, Fedor Jelezko
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. Adjustments to the dynamical nuclear polarization sequence (PulsePol) are performed, as well as slow sample rotation, to improve the NV- 13 C polarization transfer rate. The hyperpolarized 13 C NMR signal is observed in particles of 2-micrometer and 100-nanometer median sizes, with enhancements over the thermal signal (at 0.29-tesla 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.