STARTMAS: A MAS-based method for acquiring isotropic NMR spectra of spin I = 3/2 nuclei in real time

We describe a novel method, which we call STARTMAS, that allows acquisition of high-resolution or ‘isotropic’ spin I = 3/2 NMR spectra in solids in real time. Unlike the DOR technique of Samoson et al. [Mol. Phys. 65 (1988) 1013], STARTMAS is performed on a standard MAS probe and fast spinning rates are possible. The method consists of a multiple-pulse sequence interleaved with real-time data acquisition and exploits satellite (mI = ±3/2 ↔ ±1/2) and double-quantum (±3/2 ↔ ∓1/2) transitions. We show that STARTMAS experiments can be used to obtain one-dimensional DOR-like spectra or provide an ‘ultrafast’ route to high-resolution two-dimensional spectra.