Probing the quenching of rotary resonance by PISSARRO decoupling

Solid-state NMR experiments may suffer from rotary resonance recoupling (R3) due to the interference between sample spinning at a frequency νrot and rf irradiation with an amplitude ν 1 H in the vicinity of harmonic relationships ν 1 H = n ν rot where n = 1 or 2. Until recently, only the use of very high rf amplitudes (e.g., ν 1 H ≫ 2 ν rot ) made it possible to avoid such interference effects. With the advent of PISSARRO decoupling, the deleterious effects of rotary resonance recoupling can be quenched, notably for ν 1 H = 2 ν rot , so that demands on the rf amplitude ν 1 H are relaxed. Here, we discuss how PISSARRO decoupling benefits from mirror symmetry and phase-shifting. We also show that PISSARRO can cope with the chemical shift anisotropy of protons and with proton–proton dipolar interactions. PISSARRO is most effective for very fast spinning at very high static fields.