Correlated spectroscopy transverse magnetization detection

Heteronuclear correlation (HETCOR) solid-state NMR spectroscopy [54] has been widely used to provide information on the spatial proximity of different nuclei in complex spin systems. When more than one distinct / and/or S spin species is present, a 2D correlation experiment enables the detection of dipolar couplings between specific distinct IS pairs. Typically, the experiment consists of a 90° pulse that creates transverse I spin magnetization, which evolves for a time tj before it is transferred to spin S, usually via CP. The S spin FID is then detected in t2- 2D Fourier transform yields a 2D spectrum, with the appearance of cross peaks between individual I and S resonances from spins which are dipolar coupled. 

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