1H Hyperpolarization of Solutions by Overhauser Dynamic Nuclear Polarization with 13C–1H Polarization Transfer

Abstract

Dynamic nuclear polarization (DNP) is a method that can significantly increase the sensitivity of nuclear magnetic resonance. The only effective DNP mechanism for in situ hyperpolarization in solution is Overhauser DNP, which is inefficient for 1H at high magnetic fields. Here we demonstrate the possibility of generating significant 1H hyperpolarization in solution at room temperature. To counter the poor direct 1H Overhauser DNP, we implement steady-state 13C Overhauser DNP in solutions and then transfer the 13C hyperpolarization to 1H via a reverse insensitive nuclei enhanced by polarization transfer scheme. We demonstrate this approach using a 400 MHz gyrotron-equipped 3.2 mm magic angle spinning DNP system to obtain 1H DNP enhancement factors of 48, 8, and 6 for chloroform, tetrachloroethane, and phenylacetylene, respectively, at room temperature.