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

Wang, Zhuoran; Hanrahan, Michael P.; Kobayashi, Takeshi; Perras, Frédéric A.; Chen, Yunhua; Engelke, Frank; Reiter, Christian; Purea, Armin; Rossini, Aaron J.; Pruski, Marek

doi:10.1016/j.ssnmr.2020.101685

DOE OSTI · 1668253

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

Wang, Zhuoran·Hanrahan, Michael P.·Kobayashi, Takeshi·Perras, Frédéric A.·Chen, Yunhua·Engelke, Frank·Reiter, Christian·Purea, Armin·Rossini, Aaron J.·Pruski, Marek

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Abstract

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 13 C, 15 N, 113 Cd and 89 Y nuclei in functionalized mesoporous silica, CdS nanoparticles, and Y 2 O 3 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. Finally, for 89 Y, 2D idHETCOR provided 8.2 times better sensitivity than the 1 D 89 Y-detected CP experiment performed with a 3.2-mm rotor.

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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY dynamic nuclear polarization fast magic angle spinning indirect detection solid-state NMR

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Wang, Zhuoran, Hanrahan, Michael P., Kobayashi, Takeshi, Perras, Frédéric A., Chen, Yunhua, Engelke, Frank, Reiter, Christian, Purea, Armin, Rossini, Aaron J., Pruski, Marek. 2020-08-11. Combining fast magic angle spinning dynamic nuclear polarization with indirect detection to further enhance the sensitivity of solid-state NMR spectroscopy. https://doi.org/10.1016/j.ssnmr.2020.101685

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