Two-dimensional solid state methods

It is possible to generate more information rich spectra by the introduction of a second frequency dimension. Correlated two-dimensional experiments have recently been developed to extend the assignment process of solid state spectra. For instance, the solution state experiment INADEQUATE (Incredible natural abundance double quantum transfer experiment) which shows direct connectivities based on (essentially a COSY) has been found applicability for the solid state at natural C abundance [227]. 

Other methods are based on scalar heteronuclear J couplings and yield exclusively direct connectivities mediated by both multiple [229, 233] 

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