Equipment

The DNP system at Warwick is a 283 MHz Variant Infinity Plus NMR console with an Oxford 7 T (at 6.66 T) wide bore magnet and a 187 GHz high power microwave source (pictured). The NMR probe is a three channel Doty 4mm low temperature (down to 90 K) probe which can be tuned to most nuclei in double resonance mode and has been used for ¹H-¹⁵N-¹³C experiments in triple resonance mode, although this is flexible. The innovative design on this spectrometer gives great flexibility in how it runs experiments and which experiments can be performed.

Capabilities

Significant enhancements have been achieved on a large range of samples from biomolecules, >300¹, (giving a reduction in experimental time of >90000) to organic powders, >100¹, (giving a reduction in experimental time of >10000) to surface functionalised materials, >20¹, (giving a reduction in experimental time of >400) which allows surface selective measurements.

The enhancement achievable from a particular sample is difficult to predict although it is likely to be larger than 20¹. The enhancement is dependent on a large series of parameters ranging from whether the sample is soluble (if dissolving sample is not a problem), particle size, the T₁ of the sample and the polarising agent used.

¹ Compared to room temperature experiments without the polarising agent.

Papers Published on DNP NMR

2016
Dynamic Nuclear Polarization enhanced NMR at 187 GHz/284 MHz using an Extended Interaction Klystron amplifier
doi:10.1016/j.jmr.2016.01.021

2012
A spectrometer designed for 6.7 and 14.1T DNP-enhanced solid-state MAS NMR using quasi-optical microwave transmission
doi:10.1016/j.jmr.2011.12.006