优化初始脉冲增强多量子跃迁及卫星跃迁魔角旋转谱灵敏度

该文提出一个能使多量子跃迁、卫星跃迁魔角旋转及其变种方法的灵敏度明显增强的方法．在通常多量子激发或卫星跃迁激发脉冲之前施加一个预备脉冲，对初始态优化从而使循环延迟时间显著减小．利用几个代表性核种(23Na,11B和87Rb)在两个不同磁场下演示了这一方法．该方法可在低至4.7 T的磁场及6 kHz的转速下在任何常规固体核磁共振实验中实现，无需附加硬件或软件．此外，尽管完整的理论解说将另行发表，文中给出具体的实验步骤，使该方法可由用户灵活订制实验，针对每个样品优化实验参数．

Sensitivity Enhancement of Multiple Quantum and Satellite Transition Magic Angle Spinning Spectra by Optimizing the Initial State

A method to significantly enhance the sensitivity of the widely used multiple quantum magic angle spinning (MQMAS), satellite transition magic angle spinning (STMAS) and their variants is proposed. By introducing a preparatory period prior to the normal multiple quantum excitation or satellite transition pulse, the initial state can be optimized so that the recycle delay time can be substantially reduced. The performance of this method, for both MQMAS and STMAS in two different magnetic fields, has been demonstrated with a number of representative nuclear species (23Na,11B and87Rb). This method can be implemented, without any additional hardware or software accessories, on all conventional solid-state NMR spectrometers with operating magnetic field as low as 4.7 T and sample spinning speed as slow as 6 kHz. Moreover, it is a very flexible method so that it can be customized, i.e., for individual compounds, the experimental parameters can be optimized for each compound following a step-by-step procedure specified in this work although a full theoretical exposition will be provided separately.