 Magic angle spinning

Sample rotation about an axis at approximately $54.74^{\circ }$ to the field, averaging appropriate second-rank anisotropic interactions when spinning and pulse conditions are suitable.

Magic Angle Spinning (MAS) is a technique used in the field of nuclear magnetic resonance (NMR) spectroscopy, particularly for solid-state NMR. It is employed to enhance the resolution of NMR spectra of solid samples, which typically suffer from broad lines due to dipolar couplings and chemical shift anisotropy. The key concept behind MAS is to rotate the sample at a specific angle (the "magic angle," approximately 54.