Solid State Nmr With Magic Angle Spinning Exploits The Interplay Between Mechanical Rotation And Radio Frequency (rf) Pulses To Actively Switch On (recoupling) And Off (decoupling) Desired Interactions. This Intimate Interplay Also Creates An Extra Dimension Of Challenge For The Theoretical Treatments Of The Pulse Sequences, Which Require A Good Foundation Of Quantum Mechanics-- Provided By Publisher.