Improvement of homonuclear dipolar decoupling sequences in solid-state nuclear magnetic resonance utilising radiofrequency imperfections

The often annoying imperfections in the phases and pulses of typical radiofrequency multiple-pulse irradiation schemes for homonuclear dipolar decoupling are revisited and analysed here. The analysis is with respect to one such multiple-pulse sequence, namely, the windowed phase-modulated Lee-Goldburg sequence. The error terms in the Hamiltonian due to pulse imperfections may lead to effective rotation of the spins around the z-axis giving rise to image free and high-resolution H-1 spectra. Certain precautions to be taken with regard to scale factor estimation are also detailed. The analysis also points Out the range of off-set values where the best homonuclear dipolar decoupling performance of a particular pulse scheme may be obtained. (C) 2004 Published by Elsevier Inc.