Sensitivity enhancement of 29Si double-quantum dipolar recoupling spectroscopy by Carr–Purcell–Meiboom–Gill acquisition method

Abstract

An enhancement in the detection sensitivity of dipolar recoupled 29Si double-quantum magic-angle spinning experiment is shown with a Carr–Purcell–Meiboom–Gill (CPMG) train of π pulses during the acquisition period. Symmetry-adapted pulse schemes, such as POST-C7 and SR26 4 11 , are used for the double-quantum excitation. Application of POST-C7-CPMG method for framework characterisation is demonstrated in the disordered and catalytically important ZSM-5 molecular sieve. Based on the observed double-quantum dipole–dipole correlations and the known T-site Si connectivities, the assignment of all the signals is made for the orthorhombic phase of the as-synthesised (CN form) material.