Dynamics of frequency-swept nuclear spin optical pumping in powdered diamond at low magnetic fields

• Autores: Zangara, Pablo René; Dhomkar, Siddharth; Ajoy, Ashok; Liu, Kristina; Nazaryan, Raffi; Pagliero, Daniela; Suter, Dieter; Reimer, Jeffrey A.; Pines, Alexander; Meriles, Carlos A.
• Año de publicación: 2019
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: DIAMOND POWDER; HYPERPOLARIZATION; LANDAU−ZENER CROSSING; NITROGEN VACANCY CENTERS; OPTICAL SPIN PUMPING
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

A broad effort is underway to improve the sensitivity of NMR through the use of dynamic nuclear polarization. Nitrogen vacancy (NV) centers in diamond offer an appealing platform because these paramagnetic defects can be optically polarized efficiently at room temperature. However, work thus far has been mainly limited to single crystals, because most polarization transfer protocols are sensitive to misalignment between the NV and magnetic field axes. Here we study the spin dynamics of NV− 13 C pairs in the simultaneous presence of optical excitation and microwave frequency sweeps at low magnetic fields. We show that a subtle interplay between illumination intensity, frequency sweep rate, and hyperfine coupling strength leads to efficient, sweep-direction-dependent 13 C spin polarization over a broad range of orientations of the magnetic field. In particular, our results strongly suggest that finely tuned, moderately coupled nuclear spins are key to the hyperpolarization process, which makes this mechanism distinct from other known dynamic polarization channels. These findings pave the route to applications where powders are intrinsically advantageous, including the hyperpolarization of target fluids in contact with the diamond surface or the use of hyperpolarized particles as contrast agents for in vivo imaging.
Fil: Zangara, Pablo René. City University of New York; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentina
Fil: Dhomkar, Siddharth. City University of New York; Estados Unidos
Fil: Ajoy, Ashok. University of California at Berkeley; Estados Unidos. Lawrence Berkeley National Laboratory; Estados Unidos
Fil: Liu, Kristina. University of California at Berkeley; Estados Unidos. Lawrence Berkeley National Laboratory; Estados Unidos
Fil: Nazaryan, Raffi. Lawrence Berkeley National Laboratory; Estados Unidos. University of California at Berkeley; Estados Unidos
Fil: Pagliero, Daniela. City University of New York; Estados Unidos
Fil: Suter, Dieter. Universität Dortmund; Alemania
Fil: Reimer, Jeffrey A.. University of California at Berkeley; Estados Unidos. Lawrence Berkeley National Laboratory; Estados Unidos
Fil: Pines, Alexander. Lawrence Berkeley National Laboratory; Estados Unidos. University of California at Berkeley; Estados Unidos
Fil: Meriles, Carlos A.. City University of New York; Estados Unidos