Heteronuclear 1H-13C spin echoes mediated by cross-polarization

Heteronuclear spin echoes having the spin coherence transferred by means of cross-polarization (CP) under Hartmann-Hahn condition are reported. The particular characteristic of heteronuclear spin echoes is that the dephasing and refocusing processes take place within different nuclear species. Originally, they were demonstrated using the heteronuclear scalar interaction to transfer the spin coherence between the two spin systems. In this work, it is shown that spin coherence transferred by CP can also lead to the formation of heteronuclear spin echoes. A semiclassical formalism was used to explain the mechanism of generation of the spin echoes. These spin echoes were observed so far in elastomeric materials.