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Kay Saalwchter Robert Graf Hans W. Spiess 《Journal of magnetic resonance (San Diego, Calif. : 1997)》1999,140(2):471
A new approach for high-resolution solid-state heteronuclear multiple-quantum MAS NMR spectroscopy of dipolar-coupled spin-
nuclei is introduced. The method is a heteronuclear chemical shift correlation technique of abundant spins, like 1H with rare spins, like 13C in natural abundance. High resolution is provided by ultra-fast MAS and high magnetic fields, high sensitivity being ensured by a direct polarization transfer from the abundant protons to 13C. In a rotor-synchronized variant, the method can be used to probe heteronuclear through-space proximities, while the heteronuclear dipolar coupling constant can quantitatively be determined by measuring multiple-quantum spinning-sideband patterns. By means of recoupling, even weak heteronuclear dipolar interactions are accessible. The capabilities of the technique are demonstrated by measurements on crystalline
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