Research of high-resolutions NMR measurements for solid 14N spins by Dynamic Sample spinning NMR

2003年，我们试图提高动态角旋转（DAS）NMR探头中转子的旋转频率。为此，我们制作了一些具有不同盖的NMR转子，并使用转子驱动DAS系统。然而，最大转子旋转频率约为6 kHz;我们无法制造可以在超过10 kHz的旋转频率下切换旋转轴的DAS系统。因此，我们采用了不同的策略，以达到本研究的目的。首先，我们从理论上研究了泛音NMR的间接检测<23>多晶固体中的^ Na核。结果表明：当<23>用不同的辐照频率进行^ Na泛音辐照时，如果我们绘制中心跃迁强度与辐照频率的关系图，我们可以得到固体中^ Na核的高分辨率NMR谱<23>。多晶固体中的14 N核也有两个正常跃迁和一个泛音跃迁。因此，上述间接探测方法适用于固体中的14 N自旋，间接探测方法应产生高分辨率的14 N自旋NMR谱。

We tried to increase the spinning frequency of a rotor in a Dynamic Angle Spinning (DAS) NMR probe in 2003. To that end, we made some NMR rotors with different caps, and drove the DAS system using the rotors. The maximum rotor spinning frequency was, however, about 6kHz; we could not make the DAS system that can switch the spinning axis at the spinning frequency of more than 10kHz. We consequently adopted a different strategy in order to attain the objective of this study.First, we theoretically studied the indirect detection of overtone NMR for ^<23>Na nuclei in polycrystalline solids. As a result, we obtained the following findings:when the ^<23>Na overtone irradiation is performed using different irradiation frequencies, if we plot the central transition intensities against the irradiation frequencies, we can obtain a high-resolution NMR spectrum for ^<23>Na nuclei in solids.14N nuclei in polycrystalline solids also have two normal transitions and one overtone transition. Thus the above indirect detection method is applicable to the 14N spins in solids; the indirect detection method should produce high-resolution NMR spectra for 14N spins.Now, we are making a double resonance MAS probe which has two channels corresponding to a 14N resonance frequency and a 14N overtone frequency.