Multiple-quantum 13C solid-state NMR spectroscopy under moderate magic-angle spinning

A new experimental scheme for the excitation and detection of 13C multiple-quantum (MQ) NMR signals in solids under magic-angle spinning (MAS) condition is presented. Symmetry-based dipolar DQ recoupling sequences have been concatenated by π/2 pulses to generate high-order 13C MQ coherences in dipolar coupled networks. This approach generates every order of MQ coherences at moderate MAS frequencies.