Under a variety of conditions, two-point phase-modulated (TPPM) decoupling performs better than continuous-wave (CW) and composite pulse decoupling in solid state NMR. Even with relatively weak RF field strengths (<50 kHz), substantial linewidth and sensitivity enhancements are observed, and with strong decoupling fields (>100 kHz), the dipolar evolution is eliminated almost entirely. Optimal TPPM conditions may be found with minimal effort. This fact, along with the improved resonance-offset compensation and avoidance of rotor-interference effects, argues for general applicability of this sequence to strongly coupled homogeneous spin systems under magic-angle-spinning. Systems which we have studied thus far include amino acids, peptides, and nucleic acids.
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