Proton driven spin diffusion (PDSD) experiments

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13C-13C correlation based on proton driven spin diffusion

This experiment is used to enable spin diffusion among low gamma nuclei (here carbon) under MAS making use of a densely coupled proton network, a common situation in the biological and organic samples.

First, transverse 13C magnetization is created using cross polarization (CP). After that, during t1 the heteronulcear 1H-13C coupling is removed using a high power decoupling scheme, such as SPINAL64. Then a 90o pulse stores the carbon magnetisation along the z-axis. During tmix spin diffusion occurs between the carbon atoms. At the same time the proton decoupler is switched off (Proton Driven Spin Diffusion PDSD) or is replaced by a weak recoupling field (DARR/RAD) which by broadening the carbon lines greatly facilitates the spin diffusion. Typical mixing times range from 1-1000ms. Finally the second 90o pulse converts the carbon magnetisation back to the transverse plane and the FID is acquired under high power proton decoupling.

References

  1. SZEVERENYI, NM and SULLIVAN, MJ and MACIEL, GE. OBSERVATION OF SPIN EXCHANGE BY TWO-DIMENSIONAL FOURIER-TRANSFORM C-13 CROSS POLARIZATION-MAGIC-ANGLE SPINNING. JOURNAL OF MAGNETIC RESONANCE 47(3):462-475, 1982. BibTeX [1]
  2. Takegoshi, K and Nakamura, S and Terao, T. 13C-1H dipolar assisted rotational resonance in magic-angle spinning NMR. 344:631-637, 2001. BibTeX [2]

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