Efficient heteronuclear dipolar decoupling in NMR of static solid samples using phase-wiggled two-pulse phase modulation

A new scheme using phase-wiggled two-pulse phase modulation (PW-TPPM) is proposed for efficient heteronuclear dipolar decoupling in nuclear magnetic resonance (NMR) of static solid samples. The two pulses within each TPPM element have different alternating phase angles so that these elements become phase-wiggled. It is derived theoretically that such phase wiggling causes a resonance for additional averaging of the residual heteronuclear dipolar interactions and thus significantly improves decoupling efficiency in stationary solids. A static 15N-acetyl-valine crystal sample and a 15N-labeled helical peptide sample aligned in hydrated phospholipid bilayers were used to illustrate the advantages of this new scheme.