Cryogenic field-cycling instrument for optical NMR hyperpolarization studies

TL;DR

This paper introduces a cryogenic field-cycling instrument designed for optical DNP studies, capable of operating across wide temperature and magnetic field ranges, enabling detailed exploration of hyperpolarization mechanisms.

Contribution

The paper presents a novel cryogenic field-cycling device that allows comprehensive optical DNP experiments over diverse conditions, including continuous cryogen replenishment and RF pulse manipulation.

Findings

Demonstrated operation on 13C spins in diamond with NV centers

Achieved stable operation across 10mT to 9.4T and 10K to 300K

Enabled long-term, high-resolution hyperpolarization studies

Abstract

Optical dynamic nuclear polarization (DNP) offers an attractive approach to enhancing the sensitivity of nuclear magnetic resonance (NMR) spectroscopy. Efficient, optically-generated electron polarization can be leveraged to operate across a broad range of temperatures and magnetic fields, making it particularly appealing for applications requiring high DNP efficiency or spatial resolution. While a large class of systems hold promise for optical DNP, many candidates display both variable electron polarizability and electron and nuclear T1 relaxation times as functions of magnetic field and temperature. This necessitates tools capable of studying DNP under diverse experimental conditions. To address this, we introduce a cryogenic field cycling instrument that facilitates optical DNP studies across a wide range of magnetic fields (10mT to 9.4T) and temperatures (10K to 300K). Continuous cryogen replenishment enables sustained, long-term operation. Additionally, the system supports the ability to manipulate and probe hyperpolarized nuclear spins via pulse sequences involving millions of RF pulses. We describe innovations in the device design and demonstrate its operation on a model system of 13C nuclear spins in diamond polarized through optically pumped nitrogen vacancy (NV) centers. We anticipate the use of the instrument for a broad range of optical DNP systems and studies.