Demagnetizing field effects on the Hahn echo

Strong effects of modulated demagnetizing fields on the attenuation of Hahn echoes in liquids are shown theoretically as well as experimentally. As su ch demagnetizing fields are the basis of non-linear evolution leading to mu ltiple echoes, it follows that the dominating nature of such echo signals i s of a purely single-quantum character. It is concluded that the contributi on of intermolecular multiple-quantum coherence transfer echoes to the mult iple echoes is negligible. The effects shown in this study are of major imp act for NMR spectroscopy with high-field instruments as they nowadays are i n ubiquitous use. (C) 2000 Published by Elsevier Science B.V. All rights re served.