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  • 1
    Electronic Resource
    Electronic Resource
    MONETARY THEORY AND TRADE CREDIT: AN HISTORICAL APPROACH (1964)
    Oxford, UK : Blackwell Publishing Ltd
    Bulletin of economic research 16 (1964), S. 0 
    Details
    ISSN: 1467-8586
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Economics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1467-8586.1964.tb00519.x
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  • 2
    Electronic Resource
    Electronic Resource
    Spin dynamics and thermodynamics in solid-state NMR cross polarization (1986)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 84 (1986), S. 4243-4255 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We investigate spin thermodynamic processes taking place during Hartmann–Hahn cross-polarization experiments in solids, in which spin polarization is transferred between two nuclear spin species by the application of two strong rf fields. As is well known, optimum cross polarization is achieved for a particular ratio of the two rf field strengths called the Hartmann–Hahn condition; we find experimentally that this condition provides the optimum transfer not only on kinetic grounds, as is usually supposed, but also for thermodynamic reasons. By measurement of the evolution of the spin observables in a ferrocene single crystal we demonstrate the existence of a quasi-equilibrium state with nonuniform spin temperature and less than maximum entropy. A modified spin thermodynamic theory is developed whose main features are the important role of the dipolar energy for the quasi-equilibrium state and the existence of constants of the motion other than the total energy. A new cross-polarization experiment is suggested which is shown to provide efficient cross polarization even for mismatched Hartmann–Hahn conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.450046
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  • 3
    Electronic Resource
    Electronic Resource
    Multiple-quantum excitation and spin topology filtration in high-resolution NMR (1985)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 83 (1985), S. 3297-3310 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The possibility of designing pulse sequences to select NMR responses from spin systems of a given coupling topology is examined. The selection can be achieved by topology-selective multiple-quantum excitation sequences. The performance of some pulse sequences for exciting high-order multiple-quantum coherences is analyzed and verified experimentally. Treatment is given of the measurement of the intensity of multiple-quantum coherence, the sensitivity and specificity of topology-selective multiple-quantum experiments, and of the relationship between these pulse sequences and "spin editing'' methods in heteronuclear NMR. A scheme for general compensation of pulse errors is also described. Practical application of spin topology filtration to two-dimensional NMR of a small protein is demonstrated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.449189
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  • 4
    Electronic Resource
    Electronic Resource
    Erratum: Multiple-quantum excitation and spin topology filtration in high-resolution NMR [J. Chem. Phys. 83, 3297 (1985)] (1986)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 84 (1986), S. 4114-4114 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.450080
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  • 5
    Electronic Resource
    Electronic Resource
    Broad band dipolar recoupling in the nuclear magnetic resonance of rotating solids (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 98 (1993), S. 6742-6748 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The effects of homonuclear dipole couplings may be reintroduced into magic angle spinning nuclear magnetic resonance (NMR) spectra by judiciously spaced π pulse trains. This recoupling phenomenon occurs over a wide range of chemical shift differences and sample rotation speeds. We present results of magnetization exchange experiments exploiting the broad band recoupling effect, and propose a theoretical description in which pulse-assisted dipolar recoupling may be understood as a form of compensated rotational resonance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.464766
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  • 6
    Electronic Resource
    Electronic Resource
    Theory and simulations of homonuclear spin pair systems in rotating solids (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 6347-6364 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The theory of nuclear magnetic resonance (NMR) on a solid sample containing pairs of coupled homonuclear spins-1/2, rotating in a large magnetic field, is presented. The time dependence introduced by the sample rotation, in conjunction with the spin–spin coupling, makes it appear that each of the central two levels in the four-level system split into a pair of "virtual states.'' Each of the eight possible single-quantum coherences between the virtual states and the two outer levels in general contribute to the spectrum, although four of these contributions are forbidden unless a rotational resonance occurs (matching of an integer multiple of the spinning speed with the difference in isotropic shifts). Analytical line shapes for the case of vanishing shift anisotropy are given and techniques for numerical simulation in the general case demonstrated. The theory of Zeeman magnetization exchange in the presence of zero-quantum dephasing is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458314
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  • 7
    Electronic Resource
    Electronic Resource
    Two-dimensional spin–echo nuclear magnetic resonance in rotating solids (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 90 (1989), S. 679-689 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Two-dimensional spin–echo nuclear magnetic resonance (NMR) experiments on rotating powders are presented. A single π pulse in the center of the evolution period of a two-dimensional experiment produces an effective reduction of the spinning speed in an orthogonal frequency dimension. Sets of two-dimensional rotational sidebands are produced from which shielding tensors may be derived by comparison with numerical simulations. A skew projection of the 2D spectrum corresponds rigorously to the normal magic angle spinning NMR spectrum obtained at one-half the spinning speed. For small shielding tensors this corresponds to a considerable enhancement in sideband intensity, assisting the estimation of shift anisotropies without the loss in resolution associated with low actual spinning speeds. Symmetries in the intensities and phases of the 2D sidebands are shown to result from a time-domain symmetry in the powder-averaged signal. Cases where the evolution period includes two or more π pulses, and where a heteronuclear dipolar interaction is introduced, are also examined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.456147
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  • 8
    Electronic Resource
    Electronic Resource
    Rotary resonance recoupling of dipolar interactions in solid-state nuclear magnetic resonance spectroscopy (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 89 (1988), S. 692-695 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A new resonance effect in solid-state nuclear magnetic resonance (NMR) is described. The effect involves a combination of magic-angle sample rotation with irradiation of a heteronuclear spin system at the Larmor frequency of one of the spin species. If the irradiation intensity is such as to establish a match between spin nutation and sample rotation, it is shown that the heteronuclear dipolar spin interaction is selectively reintroduced into the spectrum. This allows small dipolar coupling constants to be measured in the presence of large shielding anisotropies. Applications are anticipated for determination of internuclear distances in materials lacking long-range order, such as polycrystalline materials, polymers, and surfaces.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.455191
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  • 9
    Electronic Resource
    Electronic Resource
    Enhanced double-quantum nuclear magnetic resonance in spinning solids at rotational resonance (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 96 (1992), S. 5668-5677 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The excitation efficiency of double-quantum (2Q) coherences between pairs of spin-1/2 nuclei in rotating powdered solids is greatly enhanced at rotational resonance, where an integer multiple of the spinning speed matches the difference in isotropic chemical shifts. In powdered samples it is possible to transfer up to 50% of the single-quantum magnetization through the 2Q transitions, an order of magnitude more than is achievable in magic-angle-spinning experiments performed off rotational resonance. The effect is simulated numerically by integration of the homogeneous evolution propagator and described analytically using first-order average Hamiltonian theory. Rotational resonance enhanced 2Q filtering is demonstrated experimentally for doubly 13C-labeled samples of zinc acetate and diammonium oxalate monohydrate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.462666
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  • 10
    Electronic Resource
    Electronic Resource
    Rapid methylation of microamounts of nonvolatile acids (1973)
    s.l. : American Chemical Society
    Analytical chemistry 45 (1973), S. 618-620 
    Details
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ac60325a027
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