Proton driven spin diffusion (PDSD) experiments
From NMR Wiki
| Line 23: | Line 23: | ||
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. | 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}} | + | First, transverse {{13C}} magnetization is created using [[cross polarization]] (CP). After that, during t<sub>1</sub> the heteronulcear {{1H}}-{{13C}} coupling is removed using a high power decoupling scheme, such as SPINAL64. Then a 90<sup>o</sup> pulse stores the carbon magnetisation along the z-axis. |
During t<sub>mix</sub> 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 90<sup>o</sup> pulse converts the carbon magnetisation back to the transverse plane and the FID is acquired under high power proton decoupling. | During t<sub>mix</sub> 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 90<sup>o</sup> pulse converts the carbon magnetisation back to the transverse plane and the FID is acquired under high power proton decoupling. | ||
Revision as of 22:59, 16 April 2009
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
- 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
-
Takegoshi, K and Nakamura, S and Terao, T. 13C-1H dipolar assisted rotational resonance in magic-angle spinning NMR. 344:631-637, 2001. BibTeX
