Excitation of carbon-13 triple quantum coherence in magic-angle-spinning NMR

We excite triple quantum coherence between carbon-13 nuclei in magic-angle-spinning solid state NMR, using a C7 pulse sequence applied to transverse 13C-magnetization. Experimental results on a powder of 98% labelled 13C3 l-alanine are in good agreement with analytical solutions and exact numerical simulations. We achieve a triple-quantum filtering efficiency of around 8% for the central site in the three-spin topology.