title: Tailoring broadband inversion pulses for MAS solid state NMR.
abstract: A simple approach is demonstrated for designing optimised broadband inversion pulses for MAS solid state NMR studies of biological systems. The method involves a two step numerical optimisation procedure and takes into account experimental requirements such as the pulse length, resonance offset range and extent of H(1) inhomogeneity compensation needed. A simulated annealing protocol is used initially to find appropriate values for the parameters that define the well known tanh/tan adiabatic pulse such that a satisfactory spin inversion is achieved with minimum RF field strength. This information is then used in the subsequent stage of refinement where the RF pulse characteristics are further tailored via a local optimisation procedure without imposing any restrictions on the amplitude and frequency modulation profiles. We demonstrate that this approach constitutes a generally applicable tool for obtaining pulses with good inversion characteristics. At moderate MAS frequencies the efficacy of the method is experimentally demonstrated for generating double-quantum NMR spectra via the zero-quantum dipolar recoupling scheme RFDR.
authors.affiliation: Research group-Molecular Biophysics/NMR spectroscopy, Leibniz Institute for Age Research, Fritz Lipmann Institute, D-07745, Jena, Germany.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Riedel
authors.forename: Christian
authors.initials: C
authors.lastname: Herbst
authors.forename: Jörg
authors.initials: J
authors.lastname: Leppert
authors.forename: Oliver
authors.initials: O
authors.lastname: Ohlenschläger
authors.forename: Matthias
authors.initials: M
authors.lastname: Görlach
authors.forename: Ramadurai
authors.initials: R
authors.lastname: Ramachandran
mesh_terms: D002247:Carbon Isotopes; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D012313:RNA / Q000737:chemistry
chemical_list: D002247:Carbon Isotopes; D012313:RNA