Optical pumping has been used to enhance the pulsed NMR signal of $^{129}\mathrm{Xe}$, allowing detecting low-pressure xenon gas and adsorbed on powdered solids. We observe an increase in sensitivity more than 2 orders magnitude over conventional NMR, current limitation being laser power. Adsorbed is observed at 298 K graphitized carbon (about 10 ${\mathrm{m}}^{2}$g benzanthracene (\ensuremath{\sim}0.5 ${\mathrm{m}}^{2}$g) below 170 K. The increased this technique allows study a large class...

The structure of the alkaline earth silicate glass CaSiO3 has been investigated using a two-dimensional 29Si NMR experiment that correlates isotropic magic-angle-spinning (MAS) spectrum with an anisotropic off-magic-angle-spinning spectrum. Although one-dimensional is completely unresolved, all five types SiO4 tetrahedra (represented by notation Q(n), where n = 0-4 representing number bridging oxygen) can be resolved and quantified on basis separated line shapes in 2D distribution chemical...

We describe here a new solid-state nuclear-magnetic-resonance (NMR) experiment for correlating anisotropic and isotropic chemical shifts of inequivalent nuclei in powdered samples. Spectra are obtained by processing signals arising from spinning sample, acquired independent experiments as function the angle between axis macroscopic rotation external magnetic field. This is contrast to previously proposed techniques, which were based on sudden mechanical flippings or multiple-pulse sequences....

The two-dimensional $^{17}\mathrm{O}$ dynamic-angle spinning solid-state nuclear magnetic resonance spectrum of silica glass produced from the melt was measured. From this a three-dimensional histogram correlating chemical shift, quadrupolar coupling constant, and asymmetry parameter for bridging oxygen obtained. Using existing correlations between NMR parameters local structure, distribution in mapped into histograms...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSolid-State 17O Magic-Angle and Dynamic-Angle Spinning NMR Study of the SiO2 Polymorph CoesiteP. J. Grandinetti, H. Baltisberger, I. Farnan, F. Stebbins, U. Werner, A. PinesCite this: Phys. Chem. 1995, 99, 32, 12341–12348Publication Date (Print):August 1, 1995Publication History Published online1 May 2002Published inissue 1 August 1995https://pubs.acs.org/doi/10.1021/j100032a045https://doi.org/10.1021/j100032a045research-articleACS...

We have investigated the structure of five disilicate glass compositionsK2O·2SiO2, (Na0.25K0.75 )2O·2SiO2, (Na0.50K0.50 (Na0.75K0.25)2O·2SiO2, and Na2O·2SiO2using 2D 17O Dynamic Angle Spinning (DAS) Nuclear Magnetic Resonance (NMR). The nonbridging bridging oxygen sites can be resolved in isotropic DAS spectrum. resonance shifts from 16.1 ppm K2O·2SiO2 to 11.8 Na2O·2SiO2 remains almost identical width. line shapes mixed compositions are broader with a maximum intensity that continuously...

Recent experimental developments of high-resolution NMR in solids (for example, double rotation and dynamic-angle spinning) address the reduction second-order line broadening effects, particularly systems involving quadrupolar nuclei such as 23Na, 17O, 27Al, 14N. However, some aspects theoretical description these have not been clearly understood; particular, various procedures available to truncate interactions give incompatible results. We present a general framework, based on static...

Pressure induced correlated evolution of the distributions Si–O distance and Si–O–Si inter-tetrahedral bond angle in vitreous silica quenched from pressures up to ∼14 GPa at ambient temperature is measured unprecedented detail using two-dimensional dynamic-angle-spinning 17O nuclear magnetic resonance spectroscopy. The results demonstrate that, contrast conventional wisdom, undergoes irreversible structural changes even as low ∼8 GPa. These short range involve a progressive reduction mean...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStudy of the aluminophosphate AlPO4-21 and AlPO4-25 by aluminum-27 double-rotation NMRR. Jelinek, B. F. Chmelka, Y. Wu, P. J. Grandinetti, Alexander Pines, Barrie, KlinowskiCite this: Am. Chem. Soc. 1991, 113, 11, 4097–4101Publication Date (Print):May 1, 1991Publication History Published online1 May 2002Published inissue 1 1991https://pubs.acs.org/doi/10.1021/ja00011a007https://doi.org/10.1021/ja00011a007research-articleACS PublicationsRequest...

An enhanced Rotor Assisted Population Transfer (RAPT) experiment is presented and used as a simple fast technique to measure the magnitude of nuclear quadrupolar coupling constant half-integer nuclei. The RAPT sequence consists train Gaussian pulses with alternating off-resonant frequencies +/-nuoff. Simulated experimental results demonstrating method are given in case 87Rb (spin 3/2) 27Al 5/2) also selectively suppress resonances based on their constant.

The heterometallic complex (NH3)2YbFe(CO)4 was prepared from the reduction of Fe3(CO)12 by Yb in liquid ammonia. Ammonia displaced acetonitrile solution, and crystalline compounds {[(CH3CN)3YbFe(CO)4)]2·CH3CN}∞ [(CH3CN)3YbFe(CO)4]∞ were obtained. An earlier X-ray study {[(CH3CN)3YbFe(CO)4]2·CH3CN}∞ showed that it is a ladder polymer with direct Yb−Fe bonds. In present study, an crystal structure analysis also sheetlike array Crystal data for {[(CH3CN)3YbFe(CO)4]2·CH3CN}∞: monoclinic space...

A new algorithm has been developed to simulate two-dimensional (2D) spectra with correlated anisotropic frequencies faster and more accurately than previous methods. The technique uses finite-element numerical integration on the sphere an interpolation scheme based Alderman-Solum-Grant algorithm. This method is particularly useful for calculations of joint probability distribution functions involving quantities a parametric orientation dependence. technique's efficiency also allows practical...

Gallium model systems containing four- and six-coordinate gallium sites have been investigated using solid-state NMR. Measurement of the isotropic chemical shift electric field gradient (EFG) performed at 9.4 T on alpha-Ga2O3, beta-Ga2O3, LiGaO2, NaGaO2, KGaO2, Ga2(SO4)3, LaGaO3 a variety techniques both NMR active nuclei (69Ga 71Ga) including static, high speed magic-angle spinning (MAS), satellite transition (ST) spectroscopy, rotor-assisted population transfer (RAPT). The is found to...

Adiabaticity plays a central role in modern magnetic resonance experiments, as excitations with adiabatic Hamiltonians allow precise control of the dynamics spin states during course an experiment. Surprisingly, many commonly used processes perform well even though approximation does not appear to hold throughout process. Here we show that this discrepancy can now be explained through use Berry's superadiabatic formalism, which provides framework for including finite duration process...

Two-dimensional magic angle flipping (MAF) was employed to measure the Q((n)) distribution in a (29)Si-enriched potassium disilicate glass (K(2)O.2SiO(2)). Relative concentrations of [Q((4))] = 7.2 +/- 0.3%, [Q((3))] 82.9 0.1%, and [Q((2))] 9.8 0.6% were obtained. Using thermodynamic model for species disproportionation, these relative yield an equilibrium constant k(3) 0.0103 0.0008, indicating, as expected, that is close binary glass. A Gaussian isotropic chemical shifts observed each with...

We explain how and under which conditions it is possible to obtain an efficient inversion of entire sideband family several hundred kHz using low-power, sideband-selective adiabatic pulses, we illustrate with some experimental results this framework opens new avenues in solid-state NMR for manipulating spin systems wide spinning-sideband (SSB) manifolds. This achieved through the definition criteria phase amplitude modulation designing pulse rotating solids. In turn, based on a representing...

dOp NMR resolves and differentiates formation removal of LiC₇₂ to LiC₆ as well previously undetected gas like GIC stages (precursors).