Dynamics of heteronuclear spin coupling and decoupling in solids

In solids containing two nuclear-spin species $I$ and $S$, the magnetic dipolar coupling causes exchange of order between and within the different spin subsystems. The dynamics involved are investigated theoretically by applying the memory-function approach. The experimentally observed line-broadening and line-narrowing effects in AgF and adamantane (${\mathrm{C}}_{10}$ ${\mathrm{H}}_{16}$) can be accounted for quantitatively by assuming a functional form for the memory function.