Mixed-valence compounds as polarizing agents for Overhauser dynamic nuclear polarization in solids

In this paper we investigate a novel set of polarizing agents -- mixed-valence compounds -- by theoretical and experimental methods and demonstrate their performance in high-field Dynamic Nuclear Polarization (DNP) experiments in the solid state. Mixed-valence compounds constitute a group of molecules, in which molecular mobility persists even in solids. Consequently, such polarizing agents can be used to perform Overhauser-DNP experiments in solid-state, with favorable conditions for dynamic nuclear polarization formation at ultra-high magnetic fields.