A practical guide to metal ions dynamic nuclear polarization in materials science

In this protocol we outline the practical aspects and methodology for performing metal ions-based dynamic nuclear polarization (MI-DNP), focusing on materials science applications. In MI-DNP polarization is transferred from unpaired electrons of paramagnetic metal ions to nearby nuclear spins, thereby increasing the sensitivity of NMR spectroscopy. The protocol encompasses detailed steps for (i) selecting suitable metal ion dopant based on chemical, structural and electron paramagnetic resonance (EPR) considerations, (ii) characterizing the concentration, homogeneity and EPR properties of the dopant and (iii) performing the MI-DNP experiment itself, including optimization of the field position and reliable assessment of the DNP enhancement factors. By adhering to this protocol, the interested reader can implement the MI-DNP approach in an efficient way, facilitating spectroscopic studies of functional materials.