Heteronuclear decoupling in MAS NMR in the intermediate to fast sample spinning regime.

Heteronuclear spin decoupling in solid-state magic-angle spinning NMR is investigated to present methods overcoming interferences between rf irradiation and sample spinning in the intermediate to fast spinning regime. We demonstrate that a recent phase-alternated variant of refocused CW irradiation ( r CW ApA ) provides efficient and robust decoupling in this regime. An extensive experimental and numerical comparison is presented for r CW ApA and PISSARRO (phase-inverted supercycled sequence for attenuation of rotary resonance), previously introduced to quench rotary-resonance recoupling effects, under conditions with spinning frequencies between 30 and 60 kHz. Simulations are used to identify the effect of decoupling for various nuclear spin interactions. [ABSTRACT FROM AUTHOR]