Effects of magnetic dipolar interaction on two-quantum free decay in a solid

Effects of magnetic dipolar interaction between like nuclei on two-quantum (TQ) free decay were examined in a multi-level NMR system, Al in Al2O3. TQ free decay was observed using a TQ π/2-pulse followed by a probe pulse. The effect of probe pulse was carefully examined to deduce the intrinsic decay time of the TQ coherence. The second moments for two-and three-quantum transitions were calculated. The observed decay time is in good agreement with that obtained from the calculated second moment by assuming Gaussian decay. Basic equations for TQ resonance are also presented. (author)