Combining fast magic angle spinning dynamic nuclear polarization with indirect detection to further enhance the sensitivity of solid-state NMR spectroscopy

• Published in: Solid state nuclear magnetic resonance Vol. 109; no. C; p. 101685
• Main Authors: Wang, Zhuoran, Hanrahan, Michael P., Kobayashi, Takeshi, Perras, Frédéric A., Chen, Yunhua, Engelke, Frank, Reiter, Christian, Purea, Armin, Rossini, Aaron J., Pruski, Marek
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.10.2020; Elsevier
• Subjects: Dynamic nuclear polarization; Fast magic angle spinning; Indirect detection; Solid-state NMR; Solid-state NMR; Fast magic angle spinning; Dynamic nuclear polarization; Indirect detection
• ISSN: 0926-2040; 1527-3326
• DOI: 10.1016/j.ssnmr.2020.101685

Dynamic nuclear polarization (DNP) and indirect detection are two commonly applied approaches for enhancing the sensitivity of solid-state NMR spectroscopy. However, their use in tandem has not yet been investigated. With the advent of low-temperature fast magic angle spinning (MAS) probes with 1.3-mm diameter rotors capable of MAS at 40 ​kHz it becomes feasible to combine these two techniques. In this study, we performed DNP-enhanced 2D indirectly detected heteronuclear correlation (idHETCOR) experiments on 13C, 15N, 113Cd and 89Y nuclei in functionalized mesoporous silica, CdS nanoparticles, and Y2O3 nanoparticles. The sensitivity of the 2D idHETCOR experiments was compared with those of DNP-enhanced directly-detected 1D cross polarization (CP) and 2D HETCOR experiments performed with a standard 3.2-mm rotor. Due to low CP polarization transfer efficiencies and large proton linewidth, the sensitivity gains achieved by indirect detection alone were lower than in conventional (non-DNP) experiments. Nevertheless, despite the smaller sample volume the 2D idHETCOR experiments showed better absolute sensitivities than 2D HETCOR experiments for nuclei with the lowest gyromagnetic ratios. For 89Y, 2D idHETCOR provided 8.2 times better sensitivity than the 1 D89Y-detected CP experiment performed with a 3.2-mm rotor. [Display omitted] •Dynamic nuclear polarization (DNP) and fast magic angle spinning are jointly used to boost sensitivity of solid-state NMR.•Proton-detected 2D heteronuclear correlation (idHETCOR) DNP experiments on 13C, 113Cd, 15N, and 89Y nuclei are reported.•For 15N and 89Y these experiments provide better absolute sensitivities than the DNP-enhanced 2D HETCOR experiments.