Madhu P K
Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005, India.
Solid State Nucl Magn Reson. 2009 Feb;35(1):2-11. doi: 10.1016/j.ssnmr.2008.11.001. Epub 2008 Nov 25.
High-resolution NMR spectroscopy of (1)H spins in the solid state is normally rendered difficult due to the strong homonuclear (1)H-(1)H dipolar couplings. Even under very high-speed magic-angle spinning (MAS) at ca. 60-70kHz, these couplings are not completely removed. An appropriate radiofrequency pulse scheme is required to average out the homonuclear dipolar interactions in combination with MAS to get high-resolution (1)H NMR spectrum in solid state. Several schemes have been introduced in the recent past with a variety of applications also envisaged. Development of some of these schemes has been made possible with a clear understanding of the underlying spin physics based on bimodal Floquet theory. The utility of these high-resolution pulse schemes in combination with MAS has been demonstrated for spinning speeds of 10-65kHz in a range of (1)H Larmor frequencies from 300 to 800MHz.
由于固态中氢核（¹H）自旋之间存在强烈的同核¹H-¹H偶极耦合，¹H自旋的高分辨率核磁共振光谱通常难以实现。即使在约60 - 70kHz的超高速魔角旋转（MAS）条件下，这些耦合也不能完全消除。需要一种合适的射频脉冲序列，结合MAS来平均同核偶极相互作用，从而获得固态¹H核磁共振高分辨率谱。最近已经引入了几种序列，并且还设想了各种应用。基于双峰弗洛凯理论，对潜在的自旋物理有清晰的理解，使得其中一些序列的开发成为可能。这些高分辨率脉冲序列与MAS结合的效用，已在10 - 65kHz的旋转速度以及300至800MHz范围内的一系列¹H拉莫尔频率下得到了证明。
