期刊
SOLID STATE NUCLEAR MAGNETIC RESONANCE
卷 29, 期 1-3, 页码 170-182出版社
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.ssnmr.2005.10.010
关键词
heteronuclear dipole-dipole couplings; cross-polarization; polarization transfer efficiency; signal sensitivity; glycine; diatoms; C-13 CP MAS; N-15 CP MAS; Si-29 CP MAS; TEDOR
The robustness and sensitivities of different polarization-transfer methods that exploit heteronuclear dipole-dipole couplings are compared for a series of heterogeneous solid systems, including polycrystalline tetrakis(trimethylsilyl)silane (TKS), adamantane, a physical mixture of doubly C-13,N-15-enriched and singly C-13-enriched polycrystalline glycine, and a powder sample of siliceous marine diatoms, Thalossiosira pseudonana. The methods were analyzed according to their respective frequency-matching spectra or resultant signal intensities. For a series of C-13{H-1} cross-polarization experiments, adiabatic passage Hartmann-Hahn cross-polarization (APHH-CP) was shown to have several advantages over other methods, including Hartmann-Hahn cross-polarization (HHCP), variable-amplitude cross-polarization (VACP), and ramped-amplitude cross-polarization (RACP). For X-Y systems, such as C-13{N-15}, high and comparable sensitivities were obtained by using APHH-CP with Lee-Goldburg decoupling or by using the transferred-echo double resonance (TEDOR) experiment. The findings were applied to multinuclear H-1, C-13, N-15, and Si-29 CP MAS characterization of a powder diatom sample, a challenging inorganic-organic hybrid solid that places high demands on NMR signal sensitivity. (c) 2005 Elsevier Inc. All rights reserved.
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