ja7b05194_si_001.pdf (1.89 MB)
Dynamic Nuclear Polarization Efficiency Increased by Very Fast Magic Angle Spinning
journal contribution
posted on 2017-07-10, 00:00 authored by Sachin
R. Chaudhari, Dorothea Wisser, Arthur C. Pinon, Pierrick Berruyer, David Gajan, Paul Tordo, Olivier Ouari, Christian Reiter, Frank Engelke, Christophe Copéret, Moreno Lelli, Anne Lesage, Lyndon EmsleyDynamic
nuclear polarization (DNP) has recently emerged as a tool
to enhance the sensitivity of solid-state NMR experiments. However,
so far high enhancements (>100) are limited to relatively low magnetic
fields, and DNP at fields higher than 9.4 T significantly drops in
efficiency. Here we report solid-state Overhauser effect DNP enhancements
of over 100 at 18.8 T. This is achieved through the unexpected discovery
that enhancements increase rapidly with increasing magic angle spinning
(MAS) rates. The measurements are made using 1,3-bisdiphenylene-2-phenylallyl
dissolved in o-terphenyl at 40 kHz MAS. We introduce
a source–sink diffusion model for polarization transfer which
is capable of explaining the experimental observations. The advantage
of this approach is demonstrated on mesoporous alumina with the acquisition
of well-resolved DNP surface-enhanced 27Al cross-polarization
spectra.