The magnetic field dependence of cross-effect dynamic nuclear polarization under magic angle spinning

Deni Mance; Peter Gast; Martina Huber; Marc Baldus; Konstantin L Ivanov

doi:10.1063/1.4922219

The magnetic field dependence of cross-effect dynamic nuclear polarization under magic angle spinning

J Chem Phys. 2015 Jun 21;142(23):234201. doi: 10.1063/1.4922219.

Authors

Deni Mance¹, Peter Gast², Martina Huber², Marc Baldus¹, Konstantin L Ivanov³

Affiliations

¹ NMR Spectroscopy, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, 3584 CH Utrecht, The Netherlands.
² Department of Physics, Huygens-Kamerlingh Onnes Laboratory, Leiden University, PO Box 9504, 2300 RA Leiden, The Netherlands.
³ International Tomography Center, Siberian Branch of the Russian Academy of Science, Institutskaya 3a, Novosibirsk 630090, Russia and Novosibirsk State University, Pirogova 2, Novosibirsk 63009, Russia.

PMID: 26093552
DOI: 10.1063/1.4922219

Abstract

We develop a theoretical description of Dynamic Nuclear Polarization (DNP) in solids under Magic Angle Spinning (MAS) to describe the magnetic field dependence of the DNP effect. The treatment is based on an efficient scheme for numerical solution of the Liouville-von Neumann equation, which explicitly takes into account the variation of magnetic interactions during the sample spinning. The dependence of the cross-effect MAS-DNP on various parameters, such as the hyperfine interaction, electron-electron dipolar interaction, microwave field strength, and electron spin relaxation rates, is analyzed. Electron spin relaxation rates are determined by electron paramagnetic resonance measurements, and calculations are compared to experimental data. Our results suggest that the observed nuclear magnetic resonance signal enhancements provided by MAS-DNP can be explained by discriminating between "bulk" and "core" nuclei and by taking into account the slow DNP build-up rate for the bulk nuclei.