What you will discover

An introduction to solid state DNP NMR for the non-expert will be presented in this seminar. The material covered should be of interest to those getting into the field of solids DNP or contemplating how it may be applied to their area of research to meet their research needs.

The technique of solids DNP exploits a transfer of polarization from electronic to nuclear spins. By virtue of their high gyromagnetic ratio (γ), electrons are far more polarized; transferring this larger electronic polarization to protons leads to a maximum theoretical enhancement factor of γe/γH ~ 660.

Such polarization transfer leads to increased sensitivity per unit of time. Experiments that would have taken so long as to be considered impossible previously become not only practical but time-efficient. DNP signal enhancements have been used to study biological solids like proteins, membranes, and complex biological assemblies (e.g. amyloid fibrils, viral capsids) along with a broad range of material science samples.

The instrumentation involved, from the gyrotron microwave source to the low temperature MAS probe that allows for magic angle sample spinning near 100 K, will be presented with a discussion on proper use. In addition to the hardware, unpaired electrons must be present in the sample in order to achieve a signal enhancement. With the exception of samples containing endogenous radicals, radicals or biradicals must generally be added to a DNP sample, and a variety of techniques exist to achieve a homogeneous radical distribution. Examples of these methods will be presented along with some of the tools and techniques used for sample preparation and handling.

All of this leads into a series of examples of applications to biological and material science samples, where DNP-enhanced solid state NMR was instrumental to solve solving fundamental questions.

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