SPIN DYNAMICS UNDER MAGIC-ANGLE-SPINNING BY FLOQUET FORMALISM

A new analytical method is presented for studying in a uniform way the spin dynamics in NMR experiments performed under the conditions of ma gic angle spinning. It was derived on the basis of the formalized Floq uet theory and consists in transforming the Fourier-state representati on of the NMR signal into an integral one. The;integral representation proves to be well suited in combination with Rayleigh-Schrodinger per turbation theory for both the fast and the slow spinning regimes. The corresponding perturbation expansions can be readily extended to highe r-order correction terms, which also allows the inclusion of more mode rate spinning speeds. Explicit expressions of the perturbation series were derived for both spinning regimes and applied to the case of isol ated dipolar-coupled spin-1/2 pairs for which the results can be compa red with those obtained by the exact evaluation of the equation of mot ion.