Spin-state selection in solid-state NMR
Spin-state selection in solid-state NMR is demonstrated, using similar pulse sequences as used in liquid-state NMR. The different transitions of all three carbon resonances in fully C-13-labeled L-alanine are separated in different spectra. By selecting spin-states, the contribution of the J-coupling to the linewidth is removed, leading to a considerable enhancement in resolution. The spin-state-selective technique is demonstrated for magic-angle spinning frequencies from 6 to 35 kHz. Other experimental conditions affecting the sensitivity of the experiments are discussed. Sensitivity losses due to the introduction of the spin-state-selective filter are shown to be acceptable. Finally, spin-state selection was used to experimentally confirm the differential broadening expected for the two transitions of the CH3 resonance. (C) 2003 Elsevier Science (USA). All rights reserved.