Increasing the accuracy of structural investigations by MAS spin-echo solid-state NMR experiments

The use of rotor-synchronized Hahn-echo pulse train (RS-HEPT) H decoupling, in a MAS (Magic Angle Spinning) N spin-echo NMR experiment allows the use of longer the spin-echo durations compared to the case when conventional decoupling is applied, hence enabling the accurate determination of very small J couplings down to a few Hz. Here, a thorough numerical analysis of the N spin-echo under RS-HEPT decoupling is performed with the purpose of characterizing the factors that still limit its efficiency. The obtained results are promising with respect to further improving the accuracy in the measured J couplings.