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

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 1 H at high magnetic fields. Here we demonstrate the possibility of generating significant 1 H hyperpolarization in solution at room temperature. To counter the poor direct 1 H Overhauser DNP, we implement steady-state 13 C Overhauser DNP in solutions and then transfer the 13 C hyperpolarization to 1 H 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 1 H DNP enhancement factors of 48, 8, and 6 for chloroform, tetrachloroethane, and phenylacetylene, respectively, at room temperature.