角度旋转核磁共振波谱法

魔角旋转核磁共振波谱法
NMR中有魔角效应（magic angle effect）
               魔角旋转技术（magic-angle spinning）

https://en.jinzhao.wiki/wiki/Magic_angle

The magic angle is a precisely defined angle, the value of which is approximately 54.7356°.
The magic angle is a root of a second-order Legendre polynomial, P2(cos θ) = 0, and so any interaction which depends on this second-order Legendre polynomial vanishes at the magic angle.
This property makes the magic angle of particular importance in magic angle spinning solid-state NMR spectroscopy.
In magnetic resonance imaging, structures with ordered collagen, such as tendons and ligaments, oriented at the magic angle may appear hyperintense in some sequences; this is called the magic angle artifact or effect，