Rankin, Andrew G.M., Julien Trébosc, Frédérique Pourpoint, Jean-Paul Amoureux, and Olivier Lafon. “Recent Developments in MAS DNP-NMR of Materials.” Solid State Nuclear Magnetic Resonance 101 (September 2019): 116–43.
Solid-state NMR spectroscopy is a powerful technique for the characterization of the atomic-level structure and dynamics of materials. Nevertheless, the use of this technique is often limited by its lack of sensitivity, which can prevent the observation of surfaces, defects or insensitive isotopes. Dynamic Nuclear Polarization (DNP) has been shown to improve by one to three orders of magnitude the sensitivity of NMR experiments on materials under Magic-Angle Spinning (MAS), at static magnetic ﬁeld B0 ! 5 T, conditions allowing for the acquisition of highresolution spectra. The ﬁeld of DNP-NMR spectroscopy of materials has undergone a rapid development in the last ten years, spurred notably by the availability of commercial DNP-NMR systems. We provide here an in-depth overview of MAS DNP-NMR studies of materials at high B0 ﬁeld. After a historical perspective of DNP of materials, we describe the DNP transfers under MAS, the transport of polarization by spin diffusion and the various contributions to the overall sensitivity of DNP-NMR experiments. We discuss the design of tailored polarizing agents and the sample preparation in the case of materials. We present the DNP-NMR hardware and the inﬂuence of key experimental parameters, such as microwave power, magnetic ﬁeld, temperature and MAS frequency. We give an overview of the isotopes that have been detected by this technique, and the NMR methods that have been combined with DNP. Finally, we show how MAS DNP-NMR has been applied to gain new insights into the structure of organic, hybrid and inorganic materials with applications in ﬁelds, such as health, energy, catalysis, optoelectronics etc.