Refocused linewidths less than 10 Hz in 1H solid-state NMR

Coherence lifetimes in homonuclear dipolar decoupled 1 H solid-state NMR experiments are usually on the order of a few ms. We discover an oscillation that limits the lifetime of the coherences by recording spin-echo dephasing curves. We find that this oscillation can be removed by the application of a double spin-echo experiment, leading to coherence lifetimes of more than 45 ms in adamantane and more that 22 ms in b-AspAla, corresponding to refocused linewidths of less than 7 and 14 Hz respectively