Symmetry principles for the design of radiofrequency pulse sequences in the nuclear magnetic resonance of rotating solids

Some new symmetry theorems are presented which simplify the task of designing multiple-pulse radio-frequency pulse sequences in magic-angle-spinning solid-state NMR. The symmetry theorems apply to sequences denoted R N, which n consists of N repetitions of a pulse sequence element R, alternating in phase between the values "pnrN. Each R element ideally rotates the spins by an angle p about the rotating frame x-axis. The entire R N sequence is timed to span n n rotational periods. Applications are presented for homonuclear double-quantum and zero-quantum recoupling, heteronuclear decoupling and heteronuclear recoupling. q 2000 Elsevier Science B.V. All rights reserved.