Hu B, Delevoye L, Lafon O, Trébosc J, Amoureux J P
UCCS, CNRS-8181, Lille-University, Villeneuve D'Ascq, France.
J Magn Reson. 2009 Oct;200(2):178-88. doi: 10.1016/j.jmr.2009.06.020. Epub 2009 Jun 30.
We introduce an original pulse sequence, BR2(2)(1)(taupitau), which is a block super-cycled R2(2)(1) sequence employing as basic element a pi pulse sandwiched by 'window' intervals. This homonuclear dipolar recoupling method allows the efficient excitation of double-quantum coherences between spin-1/2 nuclei submitted to very large chemical shift anisotropy. We demonstrate that this technique can be employed in double-quantum<-->single-quantum (31)P homonuclear correlation experiment at high magnetic field (B(0)>or=14 T) and high MAS frequencies (nu(R)>or=30 kHz). The performances of BR2(2)(1)(taupitau) are compared to those of the double-quantum recoupling methods, such as BABA and bracketed fp-RFDR, which were already employed at fast MAS rates. The BR2(2)(1)(taupitau) sequence displays a higher robustness to CSA and offset than the other existing techniques.
我们引入了一种原创脉冲序列BR2(2)(1)(taupitau)，它是一种块超循环R2(2)(1)序列，采用夹在“窗口”间隔之间的π脉冲作为基本单元。这种同核偶极重耦合方法能够有效激发处于非常大化学位移各向异性下的自旋1/2核之间的双量子相干。我们证明，该技术可用于高磁场（B(0)≥14 T）和高MAS频率（ν(R)≥30 kHz）下的双量子<-->单量子(31)P同核相关实验。将BR2(2)(1)(taupitau)的性能与已在快速MAS速率下使用的双量子重耦合方法（如BABA和括号内的fp-RFDR）的性能进行了比较。BR2(2)(1)(taupitau)序列对CSA和偏移的鲁棒性高于其他现有技术。
