PITANSEMA, a low-power PISEMA solid-state NMR experiment

A low radio frequency power polarization inversion spin exchange at the magic angle (PISEMA) pulse sequence is described for the measurement of heteronuclear dipolar couplings from solids. The method employs a time averaged nutation concept to significantly reduce the rf power required to spin-lock low γ nuclear spins in PISEMA experiments. The efficacy of the 2D method is demonstrated on a single crystal of n-acetyl-l-15N-valyl-l-15N-leucine dipeptide to measure 1H–15N dipolar couplings and a liquid crystal sample to measure 1H–13C dipolar couplings.