Journal ArticleDOI
Heteronuclear decoupling in rotating solids
Andrew E. Bennett,Chad M. Rienstra,Michèle Auger,Michèle Auger,K. V. Lakshmi,K. V. Lakshmi,Robert G. Griffin +6 more
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TLDR
In this article, a simple two pulse phase modulation (TPPM) scheme was proposed to reduce the residual linewidths arising from insufficient proton decoupling power in double resonance magic angle spinning (MAS) experiments.Abstract:
A simple two pulse phase modulation (TPPM) scheme greatly reduces the residual linewidths arising from insufficient proton decoupling power in double resonance magic angle spinning (MAS) experiments. Optimization of pulse lengths and phases in the sequence produces substantial improvements in both the resolution and sensitivity of dilute spins (e.g., 13C) over a broad range of spinning speeds at high magnetic field. The theoretical complications introduced by large homo‐ and heteronuclear interactions among the spins, as well as the amplitude modulation imposed by MAS, are explored analytically and numerically. To our knowledge, this method is the first phase‐switched sequence to exhibit improvement over continuous‐wave (cw) decoupling in a strongly coupled homogeneous spin system undergoing sample spinning.read more
Citations
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Metal-free four-in-one modification of g-C3N4 for superior photocatalytic CO2 reduction and H2 evolution
TL;DR: In this article , an amino functionalized ultrathin nanoporous boron-doped g-C3N4 nanosheets were used for the selective gas-phase CO2 reduction into CO with a production yield of 21.95 µmol g−1, in the absence of any cocatalyst.
Journal ArticleDOI
Synthesis and characterization of novel graft copolymers of Poly(N-vinylcarbazole) and Poly(3-methylthiophene) for optoelectronic applications
TL;DR: In this article, the synthesis and characterization of a new material based on poly(N-vinylcarbazole) and poly(3-methylthiophene) (PMeT) was reported.
Journal ArticleDOI
Solid-state 13C NMR study of the mobility of polysaccharides in the cell walls of two apple cultivars of different firmness
Jovyn K.T. Ng,Zoran D. Zujovic,Zoran D. Zujovic,Bronwen G. Smith,Jason W. Johnston,Roswitha Schröder,Laurence D. Melton +6 more
TL;DR: Solid-state (13)C nuclear magnetic resonance (NMR) was used to compare differences in mobility of the cell wall polysaccharides of 'Scifresh' and 'Royal Gala' apples after 20 weeks of storage, and unexpectedly, arabinans in 'Scafresh' cell walls were more mobile than those in 'RoyalGala' which was unforeseen considering the greater firmness of the 'Scfresh' cultivar.
Journal ArticleDOI
Deposition of thick polymer or inorganic layers with flame-retardant properties by combination of plasma and spray processes
Zeinab R. Farag,Zeinab R. Farag,Simone Krüger,Simone Krüger,Gundula Hidde,Gundula Hidde,Arnd Schimanski,Arnd Schimanski,Christian Jäger,Christian Jäger,Jörg Friedrich,Jörg Friedrich +11 more
TL;DR: In this article, the effect of different plasma parameters such as monomer/gas ratio, pressure and power input into the discharge on the deposition rate and the composition of the formed layers was studied.
Journal ArticleDOI
Improved resolution in 13C solid-state spectra through spin-state-selection
TL;DR: The application of a spin-state-selective coherence transfer experiment (INADEQUATE-SSS) to solid-state NMR spectroscopy is described and the method is demonstrated to significantly improve the spectral resolution of the crowded C'-C(alpha) region of two proteins.
References
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Journal ArticleDOI
Proton‐enhanced NMR of dilute spins in solids
TL;DR: In this article, the NMR signals of isotopically or chemically dilute nuclear spins S in solids can be enhanced by repeatedly transferring polarization from a more abundant species I of high abundance (usually protons) to which they are coupled.
Book
Principles of high-resolution NMR in solids
Abstract: 1 Introduction.- 2 Nuclear Spin Interactions in Solids.- 2.1 Basic Nuclear Spin Interactions in Solids.- 2.2 Spin Interactions in High Magnetic Fields.- 2.3 Transformation Properties of Spin Interactions in Real Space.- 2.4 Powder Spectrum Line Shape.- 2.5 The NMR Spectrum. Lineshapes and Moments.- 2.6 Magic Angle Spinning (MAS).- 2.7 Rapid Anisotropic Molecular Rotation.- 2.8 Line Shapes in the Presence of Molecular Reorientation.- 3 Multiple-Pulse NMR Experiments.- 3.1 Idealized Multiple-Pulse Sequences.- 3.2 The Four-Pulse Sequence (WHH-4).- 3.3 Coherent Averaging Theory.- 3.4 Application of Coherent Averaging Theory to Multiple-Pulse Sequences.- 3.5 Arbitrary Rotations and Finite Pulse Width in Multiple-Pulse Experiments.- 3.6 Second Averaging.- 3.7 The Influence of Pulse Imperfections on Multiple-Pulse Experiments.- 3.8 Resolution of Multiple-Pulse Experiments.- 3.9 Magic Angle Rotating Frame Line Narrowing Experiments.- 3.10 Modulation Induced Line Narrowing.- 3.11 Applications of Multiple-Pulse Experiments.- 4 Double Resonance Experiments.- 4.1 Basic Principles of Double Resonance Experiments.- 4.2 Cross-Polarization of Dilute Spins.- 4.3 Cross-Polarization Dynamics.- 4.4 Spin-Decoupling Dynamics.- 4.5 Application of Cross-Polarization Experiments.- 5 Two-Dimensional NMR Spectroscopy.- 5.1 Basic Principles of 2 D-Spectroscopy.- 5.2 2D-Spectroscopy of 13C-1H Interactions in Solids.- 5.3 Applications of 2D-Spectroscopy.- 6 Multiple-Quantum NMR Spectroscopy.- 6.1 Double-Quantum Decoupling.- 6.2 The Three-Level System Double Quantum Coherence.- 6.3 Multiple-Quantum Coherence.- 6.4 Selective Multiple-Quantum Coherence.- 6.5 Double-Quantum Cross-Polarization.- 7 Magnetic Shielding Tensor.- 7.1 Ramsey's Formula.- 7.2 Approximate Calculations of the Shielding Tensor.- 7.3 Proton Shielding Tensors.- 7.4 19F Shielding Tensors.- 7.5 13C Shielding Tensors.- 7.6 Other Shielding Tensors.- 8 Spin-Lattice Relaxation.- 8.1 Spin-Lattice Relaxation in the Weak Collision Limit.- 8.2 Spin-Lattice Relaxation in Multiple-Pulse Experiments.- 8.3 Application of Multiple-Pulse Experiments to the Investigation of Spin-Lattice Relaxation.- 8.4 Spin-Lattice Relaxation in Dilute Spin Systems.- 8.5 Selective Excitation and Spectral Diffusion.- 9 Appendix.- A Irreducible Tensor Representation of Spin Interactions.- B Rotations.- C General Line Shape Theory.- D Homogeneous, Inhomogeneous and Heterogeneous Lineshapes.- E Lineshape and Relaxation due to Fluctuating Chemical Shift Tensors.- F Time Evolution and Magnus Expansion.- G Coherent Versus Secular Averaging Theory.- H Applications of Average Hamiltonian Theory.- I Relaxation Theory.- 10 References.- 11 Subject Index.
Journal ArticleDOI
Nuclear Magnetic Resonance Spectra from a Crystal rotated at High Speed
TL;DR: In this article, it was shown that when these weak side-spectra are included the second moment does indeed remain invariant even though the second moments of the central portion, which is all that is observed experimentally, becomes smaller.
Journal ArticleDOI
Carbon-13 nuclear magnetic resonance of polymers spinning at the magic angle
Journal ArticleDOI
An improved sequence for broadband decoupling: WALTZ-16
TL;DR: In this paper, the effects of the proton irradiation sequence by means of a train of spin rotation operators, the overall effect at the end of the cycle being calculated by explicit matrix multiplication, the offset dependence of this proton response determined the residual splitting of the carbon-13 resonance and hence the effectiveness of the decoupling.