Boosting NMR sensitivity

Abstract

Poor sensitivity is one of the drawbacks of nuclear magnetic resonance spectroscopy. A method called dynamic nuclear polarization (DNP) can improve the situation, particularly for solid-state NMR, by transferring spin polarization from unpaired electrons on paramagnetic agents to the nuclei of the molecules being analyzed. This aligns the nuclei and thus boosts the NMR signal. But the electron spins are such strong magnets that they interfere with the magnetization they just induced on the nuclei, causing the boosted signal to decay quickly and broadening the peaks in the resulting spectra. Alexander B. Barnes and coworkers at Washington University in St. Louis counteract the drawbacks of the electron spins but retain the sensitivity boosts from DNP by decoupling the electron spins from the nuclear spins (J. Am. Chem. Soc. 2017, DOI: 10.1021/jacs.7b02714). To achieve that decoupling, Barnes and coworkers built a new device called a gyrotron that can rapidly switch between