Covariance spectroscopy in high-resolution multi-dimensional solid-state NMR.

Covariance spectroscopy (COV), a statistical method that provides increased sensitivity, can be applied to two-dimensional high-resolution solid-state NMR experiments, such as homonuclear spin-exchange spectroscopy. We the alternative States sampling scheme to the experimental time by 50%. By combining COV with other processing methods for non-uniform sampling (NUS), many different three-dimensional experiments can be performed with substantial increases in overall sensitivity. As an example, we show a three-dimensional homonuclear spin-exchange/separated-local-field (SLF) spectrum that enables the assignment of resonances and the measurement of structural restraints from a single experiment performed in a limited amount of time.