title: Q-shear transformation for MQMAS and STMAS NMR spectra.
abstract: The multiple-quantum magic-angle spinning (MQMAS) and satellite-transition magic-angle spinning (STMAS) experiments refocus second-order quadrupolar broadening of half-integer quadrupolar spins in the form of two-dimensional experiments. Isotropic shearing is usually applied along the indirect dimension of the 2D spectra such that an isotropic projection free of anisotropic quadrupolar broadening can be obtained. An alternative shear transformation by a factor equal to the coherence level (quantum number) selected during the evolution period is proposed. Such a transformation eliminates chemical shift along the indirect dimension leaving only the second-order quadrupolar-induced shift and anisotropic broadening, and is expected to be particularly useful for disordered systems. This transformation, dubbed Q-shearing, can help avoid aliasing problems due to large chemical shift ranges and spinning sidebands. It can also be used as an intermediate step to the isotropic representation for expanding the spectral window of rotor-synchronized experiments.
authors.affiliation: Center of Interdisciplinary Magnetic Resonance, National High Magnetic Field Laboratory, Tallahassee, FL 32310, USA.
authors.forename: Ivan
authors.initials: I
authors.lastname: Hung
authors.forename: Julien
authors.initials: J
authors.lastname: Trébosc
authors.forename: Gina L
authors.initials: GL
authors.lastname: Hoatson
authors.forename: Robert L
authors.initials: RL
authors.lastname: Vold
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Amoureux
authors.forename: Zhehong
authors.initials: Z
authors.lastname: Gan
mesh_terms: D000465:Algorithms; D016880:Anisotropy; D009682:Magnetic Resonance Spectroscopy / Q000706:statistics & numerical data*; D015233:Models, Statistical; D009556:Niobium / Q000737:chemistry; D011789:Quantum Theory; D011868:Radioisotopes; D012538:Scandium; D012815:Signal Processing, Computer-Assisted
chemical_list: D011868:Radioisotopes; D009556:Niobium; D012538:Scandium