Dynamic nuclear polarization (DNP) is a technique in which the large electron spin polarization is transferred to surrounding coupled nuclear spins via microwave (MW) irradiation.
The polarization in magnetic resonance, which determines the sensitivity of the measurement, is given by the population difference across the measured transition between two spin states. The large magnetic moment of the electrons (~650 time that of protons) means their polarization is much larger than that of any nuclei. When the electrons are coupled to surrounding nuclei their polarization can be transferred to the nuclear spins resulting in sensitivity enhancement of the NMR signal.
The electrons are typically introduced into the system of interest by adding nitroxide radicals. This approach offers large sensitivity gains, opening the way for studying very challenging systems by NMR, especially in the study of surface properties of materials.
We’re interested in using DNP for sensitivity enhancement for studying difficult (i.e. low sensitivity) nuclei as well as surface chemistry in functional materials. We are also interested in developing new polarization agents, based on paramagnetic metal ion dopants and defects, providing selectivity to the NMR measurement.
Some reviews (by other groups) on DNP for solid state NMR:
- Dynamic Nuclear Polarization Surface Enhanced NMR Spectroscopy
Aaron J. Rossini, Alexandre Zagdoun, Moreno Lelli, Anne Lesage, Christophe Copéret, Lyndon Emsley, Acc. Chem. Res., 2013, 46 (9), pp 1942–1951
- Is solid-state NMR enhanced by dynamic nuclear polarization?
Daniel Lee, Sabine Hediger, Gaël De Paëpe, Solid State Nuclear Magnetic Resonance 66-67 (2015) 6–20
- Dynamic nuclear polarization at high magnetic fields
Thorsten Maly, Galia T. Debelouchina, Vikram S. Bajaj, Kan-Nian Hu, Chan-Gyu Joo,
Melody L. Mak–Jurkauskas, Jagadishwar R. Sirigiri, Patrick C. A. van der Wel,
Judith Herzfeld, Richard J. Temkin and Robert G. Griffin J. Chem. Phys. 128, 052211 2008
- Surface Sensitive NMR Detection of the SEI Layer on Reduced Graphene Oxide
Michal Leskes, Gunwoo Kim, Tao Liu, Alison Michan, Fabien Aussenac, Patrick Dorffer, Subhradip Paul and Clare Grey J. Phys. Chem. Lett. (2017)
- Paramagnetic Metal‐Ion Dopants as Polarization Agents for Dynamic Nuclear Polarization NMR Spectroscopy in Inorganic Solids
Tanmoy Chakrabarty, Nir Goldin, Akiva Feintuch, Lothar Houben, Michal Leskes ChemPhysChem (2018)