Dynamic Nuclear Polarization: Applications to Liquid-State NMR Spectroscopy

Dynamic nuclear polarization (DNP) was first demonstrated in the early days of NMR spectroscopy. The technique involves the transfer of large spin polarization from unpaired electron spins to neighboring nuclei using microwave irradiation close to the electron Larmor frequency. Over the years, although a number of applications in solid-state NMR have been demonstrated, the use of DNP in liquid-state experiments has been more limited. Modern technological advances now mean that DNP is undergoing a rejuvenation as a technique to vastly improve the sensitivity of NMR. This article describes the current state of the art in regard to the liquid-state applications of DNP, including sensitivity enhancement in heteronuclear NMR spectroscopy.