REDOR: an assessment of the efficacy of dipolar recoupling with adiabatic inversion pulses.

A numerical assessment of the efficacy of REDOR recoupling of heteronuclear dipolar interactions employing adiabatic dephasing pulses has been carried out by considering an isolated dipolar coupled spin 1/2 I-S system. At moderate magic angle spinning frequencies in the range of 3-6 kHz and when the CSA of the dephased spins is large, it is shown that efficient broadband heteronuclear dipolar recoupling and reliable distance estimates can be achieved even under conditions where a significant fraction of the rotor period is occupied by the adiabatic pulse. The efficacy of REDOR with adiabatic inversion pulses has been demonstrated experimentally in two model 15N-13C spin systems, (13C',15N) Aib-(15N) Aib-NH2 (Aib = alpha-aminoisobutyric acid) and (1-13C,15N) glycine.