Dynamic Nuclear Polarization Surface Enhanced NMR spectroscopy (DNP SENS): Principles, protocols, and practice

Dynamic Nuclear Polarization Surface Enhanced NMR spectroscopy has been demonstrated to significantly improve NMR sensitivity on materials by 1 to 2 orders of magnitude at high magnetic fields. The preferential surface enhancement also allows for selectively probing the solid surface. In this review, we will briefly describe the main mechanism used nowadays, Le. cross effect, for DNP enhanced solid-state NMR. We will show the typical protocols of sample formulation leading to effective DNP surface enhancements and the key experimental factors in performing DNP SENS experiments. Other important developments in DNP, i.e. shielded polarizing agents for reactive surfaces, hyperpolarizing solid matrices, and high-temperature and high-field DNP, will be discussed as well. Finally, we close the review with a short summary and our perspectives on the directions of future developments in this field. (C) 2018 Elsevier Ltd. All rights reserved.