Non-resonating S-spins

In double resonance experiments, rf-pulses or pulse sequences are applied not only to the resonating 7-spins, but also to the non-resonating S-spins. Magnetic interactions between the resonating and the non-resonating nuclei, especially the heteronuclear magnetic dipole-dipole interaction, can be studied selectively by double resonance techniques. 

The so-called SEDOR technique (spin-echo double resonance [9, 47, 48], see Fig. 5) allows the determination of internuclear distances, rjs, for isolated spin pairs consisting of a resonating J-spin and a non-resonating S-spin. Hahn s echo [49] of the resonating J-spins is observed with a time between the 7i/2-pulse and the 7T-pulse. A rr-pulse applied to the S-spins after a variable time ti (0characteristic damping of Hahn s echo of the resonating /-spins. The damped amplitude, of Hahn s echo under SEDOR conditions is determined by ... 

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