The increased sensitivity can lead to additional information about the samples being studied, usually a mixture of molecules of interest, and can drastically reduce experimental acquisition times. Our group is developing an Overhauser DNP instrument at 14.1 T (corresponding to a NMR proton frequency of 600 MHz). The instrument has been built, and the effect has been demonstrated on several model compounds. The instrument is now being further developed to accommodate small molecules, such as natural products, metabolomics… It is entering the commission phase before becoming part of the MagLab user program.
In short, DNP uses microwave radiation to transfer polarization from stable radicals to NMR active nuclei in molecules of interest, thereby increasing the number of polarized nuclear spins tremendously and resulting in large signal-to-noise ratios.
This instrument is currently in its final development stage at the Tallahassee location. This system shares a gyrotron, the 395 GHz microwave source, with the MAS DNP NMR user instrument. The NMR part of the instrument is performed using an Agilent direct drive console (2 channels) in combination with an Oxford Instruments 51-mm bore 14.1-T magnet. Several probes are being developed for this system: a 3-mm HCN liquid DNP probe, a 3-mm XH liquid DNP probe, and a large-sample, 5+ mm, HX liquid DNP probe. The probes are fitted with sweep coils to finetune the magnetic field to match the resonant conditions of the radical used for Overhauser DNP experiments.
Scientific details can be found at: https://www.sciencedirect.com/science/article/pii/S1090780718300387
This instrument development effort is led by the EMR Facility.