Investigation of room temperature multispin-assisted bulk diamond 13C hyperpolarization at low magnetic fields

TL;DR

This study explores how bulk 13C nuclei in diamond can be hyperpolarized at room temperature using low magnetic fields and defect-mediated cross relaxation, with detailed analysis of polarization decay and coupling mechanisms.

Contribution

It introduces a novel approach to achieve and analyze room temperature 13C hyperpolarization in diamond via multispin-assisted processes at low magnetic fields.

Findings

Hyperpolarization persists above thermal equilibrium.

Decay rates vary with magnetic field strength.

Coupling distances and mechanisms are identified.

Abstract

In this work we investigated the time behavior of the polarization of bulk 13C nuclei in diamond above the thermal equilibrium. This nonthermal nuclear hyperpolarization is achieved by cross relaxation between two nitrogen related paramagnetic defect species in diamond in combination with optical pumping. The decay of the hyperpolarization at four different magnetic fields is measured. Furthermore, we use the comparison with conventional nuclear resonance measurements to identify the involved distances of the nuclear spin with respect to the defects and therefore the coupling strengths. Also, a careful look at the linewidth of the signal give valuable information to piece together the puzzle of the hyperpolarization mechanism.