نتایج جستجو برای: quadrupolar nuclei
تعداد نتایج: 62901 فیلتر نتایج به سال:
Chemically informative J couplings between pairs of quadrupolar nuclei in dimetallic and dimetalloid coordination motifs are measured using J-resolved solid-state NMR experiments. It is shown that the application of a double-quantum filter is necessary to observe the J splittings and that, under these conditions, only a simple doublet is expected. Interestingly, the splitting is amplified if th...
The study of biologically active and other organic compounds by solid-state NMR has for the most part been limited to spin-1/2 nuclei such as H, C, N, F, and P. The study of O, a quadrupolar nucleus (S = 5/2), in solid organic compounds has been limited due to its low natural abundance, low magnetogyric ratio, and strong secondorder quadrupolar interactions. The first two difficulties can be al...
In this paper we present a series of high-resolution zero-field NMR spectra of the polycrystalline intermetallic compound GdAl(2). The spectra were obtained with the sample at 4.2K in the ordered magnetic state and in the absence of an external static magnetic field. Using a sequence composed of two RF pulses, we obtained up to five multi-quantum echoes for the (27)Al nuclei, which were used to...
Through-space heteronuclear correlation (D-HETCOR) experiments based on multiple-quantum (D-HMQC) and refocused insensitive nuclei enhanced by polarization transfer (D-RINEPT) sequences have been proven to be useful approaches for the detection of spatial proximity between half-integer quadrupolar in solids under magic-angle spinning (MAS) conditions. The corresponding pulse employ coherence tr...
We discuss the potential use of relaxation times toward the resolution of inequivalent chemical sites in the NMR spectroscopy of powdered or disordered samples. This proposal is motivated by the significant differences that can often be detected in the relaxation behavior of sites in solids, particularly when focusing on NMR observations of quadrupolar nuclei possessing different coordination a...
The observation of a double-quantum filtered signal of quadrupolar nuclei (e.g. (23)Na) in solution has been traditionally interpreted as a sign for anisotropic reorientational motion. Ling and Jerschow (2007) have found that a (23)Na double-quantum signal is observed also in solutions of TmDOTPNa(5). Interference effects between the quadrupolar and the paramagnetic interactions have been repor...
Nitrogen is one of the most abundant elements and plays a key role in the chemistry of biological systems. Despite its widespread distribution, the study of the naturally occurring isotope of nitrogen, (14)N (99.6%), has been relatively limited as it is a spin-1 nucleus that typically exhibits a large quadrupolar interaction. Accordingly, most studies of nitrogen sites in biomolecules have been...
We have investigated the suitability and performance of various decoupling methods on systems in which an observed spin-1/2 nucleus I (13C or 15N) is scalar-coupled to a quadrupolar spin S (2H). Simulations and experiments have been conducted by varying the strength of the irradiating radiofrequency (RF) field, RF offset, relaxation times, and decoupling schemes applied in the vicinity of the S...
The spin lattice relaxation of I = 3/2 quadrupolar spin system due to domain walls in order-disorder ferroelectrics has been studied and a general method is proposed for the measurement of domain width in nano ferroelectrics. Based on the fact that electric polarization undergoes spiral orientation as one moves from one domain to the other, it is assumed that at low temperatures the spins at an...
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