title: Numerical design of RN(n)(nu) symmetry-based RF pulse schemes for recoupling and decoupling of nuclear spin interactions at high MAS frequencies.
abstract: An approach for the efficient implementation of RN(n)(nu) symmetry-based pulse schemes that are often employed for recoupling and decoupling of nuclear spin interactions in biological solid state NMR investigations is demonstrated at high magic-angle spinning frequencies. RF pulse sequences belonging to the RN(n)(nu) symmetry involve the repeated application of the pulse sandwich {R(phi)R(-phi)}, corresponding to a propagator U(RF) = exp(-i4phiI(z)), where phi = pinu/N and R is typically a pulse that rotates the nuclear spins through 180 degrees about the x-axis. In this study, broadband, phase-modulated 180 degrees pulses of constant amplitude were employed as the initial 'R' element and the phase-modulation profile of this 'R' element was numerically optimised for generating RN(n)(nu) symmetry-based pulse schemes with satisfactory magnetisation transfer characteristics. At representative MAS frequencies, RF pulse sequences were implemented for achieving 13C-13C double-quantum dipolar recoupling and through bond scalar coupling mediated chemical shift correlation and evaluated via numerical simulations and experimental measurements. The results from these investigations are presented here.
authors: Research group Biomolecular NMR spectroscopy, Leibniz Institute for Age Research, Fritz Lipmann Institute, 07745 Jena, Germany.
authors: Christian
authors: C
authors: Herbst
authors: Jirada
authors: J
authors: Herbst
authors: Jörg
authors: J
authors: Leppert
authors: Oliver
authors: O
authors: Ohlenschläger
authors: Matthias
authors: M
authors: Görlach
authors: Ramadurai
authors: R
authors: Ramachandran
mesh_terms: D002247:Carbon Isotopes / Q000737:chemistry; D003198:Computer Simulation; D008956:Models, Chemical; D009587:Nitrogen Isotopes / Q000737:chemistry; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*
chemical_list: D002247:Carbon Isotopes; D009587:Nitrogen Isotopes