Rotating frame heteronuclear dipolar

Fig. 2. A 2D SLF pulse sequence (A) with S-spin magnetization evolution (B) subject only to heteronuclear dipolar couplings in the q period and detection of chemical shift spectrum in the 2 period. Various multiple pulse (MP) sequences can be used to suppress dipolar coupling among I spins in the laboratory frame during the h period, which enables line-narrowing in the I-S dipolar coupling dimension (i.e., the a>i frequency dimension of the 2D spectrum). This experiment under MAS can be used for separating I-S dipolar sideband patterns by isotropic chemical shifts the re-pulse and the start of the acquisition need to be synchronized with rotational echoes. Other aspects of this pulse sequence are similar to the SLF sequence in Fig. 1.

Heteronuclear incoherent magnetization transfer is the transfer of longitudinal magnetization. It can proceed in the laboratory frame and in the rotating frame. The nuclear Overhauser effect (NOE) [Nogl] is a manifestation of polarization tranter in the laboratory frame. In the extreme narrowing limit saturation of dipolar relaxation of the I doublet of a heteronuclear IS two-spin- system leads to an enhancement of the S-spin polarization by a factor... 

K. Yamamoto, S. V. Dvinskikh, and A. Ramamoorthy, Measurement of heteronuclear dipolar couplings using a rotating frame solid-state NMR experiment, Chem. Phys. Lett. 

The technique applied most frequently for heteronuclear dipolar recoupling is cross polarization. Heteronuclear dipolar interactions can facilitate polarization transfer between spins in the doubly rotating frame if two rf spinlock fields with appropriate field strengths are applied simultaneously on both channels. The ratio between the rf field amplitudes and on the proton and the heteronuclear rf channel under MAS at a spinning frequency Vrai has to match the Hartmann-Hahn condition ... 

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