Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
J Phys Chem Lett. 2022 Aug 25;13(33):7749-7755. doi: 10.1021/acs.jpclett.2c01956. Epub 2022 Aug 15.
Dynamic nuclear polarization (DNP) is a method that can significantly increase the sensitivity of nuclear magnetic resonance. The only effective DNP mechanism for hyperpolarization in solution is Overhauser DNP, which is inefficient for H at high magnetic fields. Here we demonstrate the possibility of generating significant H hyperpolarization in solution at room temperature. To counter the poor direct H Overhauser DNP, we implement steady-state C Overhauser DNP in solutions and then transfer the C hyperpolarization to 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 H DNP enhancement factors of 48, 8, and 6 for chloroform, tetrachloroethane, and phenylacetylene, respectively, at room temperature.
动态核极化（DNP）是一种可以显著提高核磁共振灵敏度的方法。在溶液中实现超极化的唯一有效 DNP 机制是 Overhauser DNP，但在高磁场下对 H 效率不高。在这里，我们证明了在室温下溶液中产生显著 H 超极化的可能性。为了克服直接 H Overhauser DNP 的不足，我们在溶液中实现了稳态 C Overhauser DNP，然后通过反不敏感核增强极化转移方案将 C 极化转移到 H 上。我们使用配备 400 MHz 回旋管的 3.2 毫米魔角旋转 DNP 系统来演示这种方法，在室温下分别获得了氯仿、四氯乙烷和苯乙炔的 H DNP 增强因子为 48、8 和 6。
