The performance of phase modulated heteronuclear dipolar decoupling schemes in fast magic-angle-spinning nuclear magnetic resonance experiments

The experimental performance of the phase modulated decoupling schemes SDROOPY-1 and SPINAL64 is investigated for heteronuclear dipolar decoupling in solid-state magic-angle-spinning nuclear magnetic resonance (NMR), in comparison with existing decoupling methods. It is found that both sequences perform well over a range of spinning rates from 0 to 35 kHz, with linewidths that are virtually independent of the spinning rate. The signal intensity is found to diminish with increasing spinning rate, and this behavior is compared qualitatively with theory. It is also demonstrated that decoupling sequences strongly influence the refocused linewidths observed in solid-state NMR, and that SDROOPY-1 and SPINAL64 both yield particularly long dephasing times. (C) 2003 American Institute of Physics.