title: Double-quantum filtered MAS NMR in the presence of chemical shielding anisotropies and direct dipolar and J couplings.
abstract: Double-quantum filtered MAS NMR spectra of an isolated homonuclear spin-1/2 pair are considered, at and away from rotational resonance conditions. The pulse sequence used is the solid-state NMR equivalent of double-quantum filtered COSY, known from solution-state NMR. The 119Sn spin pair in [(chex3Sn)2S] is characterized by a difference in isotropic chemical shielding smaller than the two chemical shielding anisotropies and by direct dipolar and isotropic J-coupling constants of similar magnitudes. At rotational resonance, one-dimensional double-quantum filtered 119Sn lineshapes yield the relative orientation of the two 119Sn chemical shielding tensors. Good double-quantum filtration efficiencies are found at and away from rotational resonance conditions, despite the presence of large chemical shielding anisotropies. Numerical simulations illustrate the interplay of the direct dipolar and J-coupling pathways and identify the latter as the main pathway even at rotational resonance conditions.
authors.affiliation: Baverisches Geoinstitut, Universität Bayreuth, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Bechmann
authors.forename: Xavier
authors.initials: X
authors.lastname: Helluy
authors.forename: Claire
authors.initials: C
authors.lastname: Marichal
authors.forename: Angelika
authors.initials: A
authors.lastname: Sebald
mesh_terms: D016880:Anisotropy; D007554:Isotopes; D009682:Magnetic Resonance Spectroscopy; D014001:Tin
chemical_list: D007554:Isotopes; D014001:Tin