Showing papers in "Journal of Magnetic Resonance in 1981"

TL;DR: In this paper, the two-dimensional Fourier transform was applied to a sample of 9-hydroxytricyclodecan-2,5-dione.

TL;DR: In this paper, it was shown that spin-spin couplings can lead to J cross-peak in analogy to cross-peaks in two-dimensional autocorrelated spectroscopy.

TL;DR: In this paper, the authors proposed to use phase cycling of the proton and carbon-13 transmitter pulses, similar to that recently introduced in homonuclear correlation experiments, allowing positive and negative f, frequencies to be distinguished.

TL;DR: In this article, the authors proposed a spin echo correlated spectroscopy (SECSY) technique to identify the resonances connected by a scalar spin-spin coupling in the two-dimensional Fourier transform NMR spectrum.

TL;DR: In this paper, the authors investigated important 13C line-broadening mechanisms in organic solids and their dependences on experimental parameters, notably static and rf magnetic field strength, and showed that no significant gain in resolution will be enjoyed at high magnetic fields, especially when variable-temperature operation is available.

TL;DR: In this article, the double-quantum coherence of carbon-13 pairs of interacting carbon-14 nuclei is determined by measuring the chemical shifts of the two carbon sites, measured with respect to the transmitter frequency.

TL;DR: In this article, the authors proposed a composite pulse scheme to compensate the effects of pulse length errors due to spatial inhomogeneity of the radiofrequency field, which was tested on the proton spectrum of 1,1,2 trichloroethane with deliberately misset refocusing pulses; gross fluctuations in intensity are observed unless the composite pulses are used.

TL;DR: In this paper, the Fourier transform of the solid-echo decay is compared with those from the free-induction decay in the slow-motion region where the motional correlation times are of the same order as the reciprocal anisotropic spin interactions.

TL;DR: In this article, a new class of multipulse sequences specifically designed for low-power requirements is introduced, and it is found that of all sequences tested BR-24 leads to optimum performance.

TL;DR: In this article, the influence of molecular packing on isotropic chemical shifts (ICS) in solids is probed experimentally, and it is suggested that until solid-state chemical shifts are better understood, care should be taken in attributing observed shifts (less than 2 ppm) for a given carbon to changes in conformation or specific interactions.

TL;DR: In this article, the authors proposed a novel expt. is referred to as accordion spectroscopy, in which the dimension is reduced from 3 to 2 by synchronous incrementation of evolution period t, and the mixing time tm parameters: tm = Kt1.

TL;DR: In this paper, a series of spin-echo Fourier transform (SEFT) experiments are described with which 13 C NMR spectra can be simplified and resonances assigned to methyl, methylene, methine, and quaternary carbon sites.

TL;DR: In this article, the electron spin-echo signal decay of paramagnetic centers induced by their dipole-dipole interaction modulated simultaneously by the processes of random spin flips and microwave pulses is analyzed.

TL;DR: In this article, a two-dimensional Fourier transform was used to detect the relative sign of the spin coupling constants in high-resolution NMR spectra, which can be used as a diagnostic tool in the recognition of geminal and vicinal proton-proton couplings.

TL;DR: In this article, the authors derived approximate analytical expressions for the relaxation rates for the spin I = 5 2 and 7 2 and tested them against the experimentally accessible apparent relaxation rates, for a fast-exchange two-state model.

TL;DR: In this article, the effect of a steady gradient on the stability of the spin echo in NMR pulsed-gradient (g) diffusion measurements was examined quantitatively and shown to give an improvement in stability if g0 ∥ g.

TL;DR: In this paper, a multinuclear double-tuned probe using lumped-element construction is compared and contrasted with a transmission line probe, and a rationale for improved efficiency at the high frequency and a commensurate improvement in the signal-to-noise ratio is developed.

TL;DR: In this paper, exact analytic expressions for the modulation effects in two-and three-pulse electron spin echoes resulting from the hyperfine interaction of an electron and a nucleus with an arbitrary spin are derived.

TL;DR: In this article, a probe suitable for 270-MHz 1H NMR in solids is described, using the combination of the phase error-compensated WAHUHA multiple-pulse cycle and magic-angle sample spinning (MAS).

TL;DR: In this article, it was shown that the enhancement of the components of the I multiplet varies with τ as Σ m I m I sin (4 πJm I τ ) where J is the scalar coupling constant and m I takes the values l, l - l, …, -l.

TL;DR: In this article, the effects of oxygen-dependent shortening of the electron spin relaxation times of nitroxide spin labels were studied in dispersions of dimyristoylphosphatidylcholine (DMPC) and dipalmitoyl-phosphate-morphosynthetic choline (DPPC).

TL;DR: In this article, the Jeener-Broekaert pulse sequence is considered as an alternative to selective and nonselective pulse experiments for relaxation measurements in partially ordered spin systems, and it is demonstrated that measurements of the decay of the sum and difference magnetizations provide a convenient method for the simultaneous determination of J1(ω0) and J2(2ω0).

TL;DR: Triangular multiplication is a computational routine for improvement of two-dimensional nuclear Overhauser enhancement and twodimensional correlated spectra The routine is applied after Fourier transformation in both dimensions.