화학공학소재연구정보센터
Journal of the American Chemical Society, Vol.139, No.18, 6310-6313, 2017
Electron Decoupling with Dynamic Nuclear Polarization in Rotating Solids
Dynamic nuclear polarization (DNP) can enhance NMR sensitivity by orders of magnitude by transferring spin polarization from electron paramagnetic resonance (EPR) to NMR However, paramagnetic DNP polarizing agents can have deleterious effects on NMR signals. Electron spin decoupling can mitigate these paramagnetic relaxation effects. We demonstrate electron decoupling experiments in conjunction with DNP and magic-angle-spinning NMR spectroscopy. Following a DNP and spin diffusion period, the microwave irradiation frequency is quickly tuned on-resonance with electrons on the DNP polarizing agent. The electron decoupling performance shows a strong dependence on the microwave frequency and DNP polarization time. Microwave frequency sweeps through the EPR line shape are shown as a time domain strategy to significantly improve electron decoupling. For C-13 spins on biomolecules frozen in a glassy matrix, electron decoupling reduces the line widths by 11% (47 Hz) and increases the intensity by 14%.