A. Goldbourt et al., Enhanced conversion of triple to single-quantum coherence in the triple-quantum MAS NMR spectrosocopy of spin-5/2 nuclei, CHEM P LETT, 320(5-6), 2000, pp. 448-456
A new type of fast amplitude modulated pulse scheme is presented here that
yields a significant sensitivity enhancement in the triple-quantum magic an
gle spinning NMR spectrum of a spin-5/2 nucleus. Enhancement is achieved by
fast phase alternation of the triple to single-quantum conversion pulse, w
hich transfers triple to single-quantum coherence in a direct, non-adiabati
c manner. The success of this pulse relies on the difference between the qu
adrupolar frequency and the intensity of the rf irradiation field, during i
ts short segments. Numerical optimizations and experimental results are pre
sented showing the improved performance. (C) 2000 Elsevier Science B.V. All
rights reserved.