A soln. is presented to the problem of phase dispersion in the resultant magnetization for pulses used for high-resoln. NMR work by demonstrating how a Gaussian pulse having an on-resonance flip angle of 270 Deg has much improved phase properties over the conventional 90 Deg Gaussian pulse. Since the whole pulse is soft, the coupling partners of a multiplet are not affected, and the evolution of the magnetization due to couplings will be refocused in exactly the same way as if it were due to chem. shifts. An illustrative spectrum of a mixt. of cis- and trans-2-phenylcyclopropanecarboxylic acid Me ester obtained with a hard 90 Deg pulse is presented. [on SciFinder (R)]
Lothar Helm, Pascal Miéville, Hugues Jaccard