%0 Journal Article %J Journal of Chemical Physics %D 1998 %T Time-reversal of cross-polarization in nuclear magnetic resonance %A Ernst, M. %A Meier, B. H. %A Tomaselli, M. %A Pines, A. %K echoes %X
It is demonstrated that the time evolution of the heteronuclear polarization-transfer process in a dipolar-coupled nuclear spin system can be reversed, leading to the observation of cross polarization echoes. The cross-polarization echoes are induced by consecutive application of two pulse trains that produce effective Hamiltonians that differ only in sign, Cross-polarization echoes have been recorded for a powder sample of alanine. The time evolution of the spin;system is consistent with both unitary quantum dynamics and with spin thermodynamics of two systems approaching a common spin temperature. (C) 1998 American Institute of Physics.
%B Journal of Chemical Physics %V 108 %P 9611-9613 %8 Jun 15 %@ 0021-9606 %G English %U