Gj. Boender et al., A physical interpretation of the Floquet description of magic angle spinning nuclear magnetic resonance spectroscopy, MOLEC PHYS, 95(5), 1998, pp. 921-934
A physical interpretation of the Floquet description for magic angle spinni
ng (MAS) nuclear magnetic resonance (NMR) is proposed. The effect of the sp
atial rotation on the spin system in sample spinning is analysed and descri
bed in terms of orbital angular momentum operators. The analogy between rot
ations in real space and in spin space is emphasized. The transformation pr
operties of the irreducible tensors in real space are used to construct a F
loquet Hamiltonian for MAS NMR, that is time independent and comprises one
term associated with pure sample rotation. The remaining terms are associat
ed with the spin system, and consist of spin-phonon type Floquet operators
generating simultaneous transitions between rotational states and spin stat
es. Finally, two different definitions for the Floquet density operator are
compared.