Dynamic Nuclear Polarization (DNP)

Adressing the sensitivity issue of nuclear magnetic resonance has been a long-standing goal and has continuously driven the community towards higher static magnetic fields, new detection technologies, and more complex radio frequency excitation schemes. Dynamic nuclear polarization (DNP) can significantly enhance the NMR signal by transferring the higher polarization from a polarizing agent (namely a paramagnetic center) to the target nuclei. In the liquid state at room temperature, the addition of stable organic radicals and irradiation of their electronic transitions via microwave can lead to NMR-signal enhancements up to two or three orders of magnitude. Our goal is to integrate DNP for routine NMR spectroscopy in the liquid state at room temperature, and then contribute to the development of the next generation of NMR methods.

The polarization transfer process critically depends on the chosen polarizing agent / target system as well as on the external magnetic field. Specifically, molecular diffusion, molecular collisions, structural reorientations, and transient bonding/complexations, all contribute to the DNP efficiency by modulating the hyperfine coupling between electron and nuclei. We aim at a deep understanding of the polarization transfer mechanisms in the liquid state. By using DNP instruments at different magnetic fields (0.34 T, 1.2 T, 3.4 T, and 9.4 T) we are characterizing new targets and polarizing agents to identify suited conditions to boost the NMR enhancements.