Grating spin echoes

Single-quantum proton spin coherences produced by a single radio-frequency pulse and evolving in a spatially modulated, external magnetic field were examined theoretically and experimentally in water. It is shown that the coherences are multiply refocused in the form of "grating echoes". The theoretical treatment describes and explains the phenomena in detail. The fact that this sort of new and unconventional spin echoes can be observed sheds new light on our understanding of other spin coherence phenomena such as the so-called "multiple echoes" first described by G. Deville, M. Bernier, J. M. Delrieux (Phys. Rev. B 19, 5666, 1979).