title: Multiple-rotor-cycle 2D PASS experiments with applications to (207)Pb NMR spectroscopy.
abstract: Thetwo-dimensional phase-adjusted spinning sidebands (2D PASS) experiment is a useful technique for simplifying magic-angle spinning (MAS) NMR spectra that contain overlapping or complicated spinning sideband manifolds. The pulse sequence separates spinning sidebands by their order in a two-dimensional experiment. The result is an isotropic/anisotropic correlation experiment, in which a sheared projection of the 2D spectrum effectively yields an isotropic spectrum with no sidebands. The original 2D PASS experiment works best at lower MAS speeds (1-5 kHz). At higher spinning speeds (8-12 kHz) the experiment requires higher RF power levels so that the pulses do not overlap. In the case of nuclei such as (207)Pb, a large chemical shift anisotropy often yields too many spinning sidebands to be handled by a reasonable 2D PASS experiment unless higher spinning speeds are used. Performing the experiment at these speeds requires fewer 2D rows and a correspondingly shorter experimental time. Therefore, we have implemented PASS pulse sequences that occupy multiple MAS rotor cycles, thereby avoiding pulse overlap. These multiple-rotor-cycle 2D PASS sequences are intended for use in high-speed MAS situations such as those required by (207)Pb. A version of the multiple-rotor-cycle 2D PASS sequence that uses composite pulses to suppress spectral artifacts is also presented. These sequences are demonstrated on (207)Pb test samples, including lead zirconate, a perovskite-phase compound that is representative of a large class of interesting materials.
authors.affiliation: Department of Chemistry, The Pennsylvania State University, 152 Davey Laboratory, University Park, Pennsylvania 16802-6300, USA.
authors.forename: F G
authors.initials: FG
authors.lastname: Vogt
authors.forename: J M
authors.initials: JM
authors.lastname: Gibson
authors.forename: D J
authors.initials: DJ
authors.lastname: Aurentz
authors.forename: K T
authors.initials: KT
authors.lastname: Mueller
authors.forename: A J
authors.initials: AJ
authors.lastname: Benesi
mesh_terms: D007554:Isotopes; D007854:Lead; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*
chemical_list: D007554:Isotopes; D007854:Lead