Unified representation of MQMAS and STMAS NMR of half-integer quadrupolar nuclei

High resolution solid state NMR has been achieved for nuclei that exhibit quadrupolar interaction to the second order by MQMAS and more recently by STMAS. Both methods extend to several variants, 3QMAS, 5QMAS, … for MQMAS as well as ST1MAS, ST2MAS,… for STMAS. These experiments contain the same information content i.e. anisotropic second-order powder pattern and isotropic terms. A unified representation allows us to display the 2D spectra independently of the method used. Direct comparison of any such spectra is therefore straightforward and does not need any further renormalization.