title: Floquet-van Vleck analysis of heteronuclear spin decoupling in solids: the effect of spinning and decoupling sidebands on the spectrum.
abstract: We investigate the effect of magic angle spinning on heteronuclear spin decoupling in solids. We use an analytical Floquet-van Vleck formalism to derive expressions for the powder-averaged signal as a function of time. These expressions show that the spectrum consists of a centerband at the isotropic frequency of the observed spin, omega(0), and rotational decoupling sidebands at omega(0)+/-omega(1)+/-momega(r), where omega(1) is the decoupling field strength and omega(r) is the rotation frequency. Rotary resonance occurs when the rotational decoupling sidebands overlap with the centerband. Away from the rotary resonance conditions, the intensity of the centerband as a function of omega(r)/omega(1) is simply related to the total intensity of the rotational decoupling sidebands. Notably, in the absence of offset terms it is shown that as omega(1) decreases, the centerband intensity can decrease without any associated broadening. Furthermore, the centerband width is shown to be independent of spinning speed, to second order for the effects we consider. The effects of I spin chemical shift anisotropy and homonuclear dipolar couplings are also investigated. The analytical results are compared to simulations and experiments.
authors.affiliation: Otterbein College, Chemistry Department, Westerville, OH 43081, USA. jsachleben@otterbein.edu
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Sachleben
authors.forename: Janet
authors.initials: J
authors.lastname: Gaba
authors.forename: Lyndon
authors.initials: L
authors.lastname: Emsley
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D005583:Fourier Analysis; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008956:Models, Chemical; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D013057:Spectrum Analysis / Q000379:methods*; D013113:Spin Labels
chemical_list: D013113:Spin Labels