Temperature and Density Dependence of the Local Magnetic Field in Dense Xenon Gas

Kanegsberg, Edward; Pass, Brendan; Carr, H. Y.

doi:10.1103/physrevlett.23.572

Cited by 34 publications

(16 citation statements)

References 8 publications

(2 reference statements)

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“…They found that the xenon chemical shift has a very large temperature dependence, ranging from 0.678 ppm/amagat at 240 K down to 0.472 ppm/amagatat 440 K which they fit by adding a temperature dependence to their virial expansion coefficients for the xenon chemical shift [37]. Their results are more accurate and differ considerably from earlier temperature measurements by Carr and coworkers [41]. Xenon …”

Section: Temperature Dependencescontrasting

confidence: 52%

Optical pumping and xenon NMR

Raftery¹

1991

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Nuclear Magnetic Resonance (NMR) spectroscopy of xenon has become an important tool for jnvestigating a wide variety of materials, especially those with high surface area. The sensitivity of its chemical shift to environment, and its chemical inertness . and adsorption properties make xenon a particularly useful NMR probe. This work discusses the application of optical pumping to enhance the sensitivity of xenon NMR " experiments, thereby allowing them to be Used in the study of systems with lower surface area.A novel method of optically-pumping 129Xe in low magnetic field below an NMR spectrometer and subsequent transfer of the gas to high magnetic field is described.NMR studies of the highly polarized gas adsorbed onto powdered samples with low to moderate surface areas are now possible. For instance, NMR studies of optically~ pumped xenon adsorbed onto polyacrylic acid show that xenon has alarge interaction with the surface. By modeling the low temperature data in terms of a sticking probability and the gas phase xenon-xenon interaction, the diffusion coefficient for xenon at the surface of the polymer is determined. The sensitivity enhancement afforded by optical pumping also allows the NMR observation of xenon thin films frozen onto the inner surfaces of different sample cells. The geometry of the thin films results in interesting line shapes that are due to the bulk magnetic susceptibility of xenon.Experiments are also descriped that combine optical pumping with optical detection for high sensitivity in low magnetic field to observe the quadrupolar evolution of 131 Xe spins at the surface of the pumping cell~. In cells with macroscopic asymmetry, a residual quadrupolar interaction causes a splitting in the 131XeNMR frequencies in bare Pyrex glass cells and cells with added hydrogen.Conventional xenon NMR experiments conducted on coadsorbed organic molecules _ in Na-Y zeolites show that the xenon chemical shift is sensitive to the identity and concentration of these guests. Clusters of xenon trapped in Na-A zeolite have interesting statistical distributions due to the finite atomic size of the xenon. The statistics can be described in the low to moderate loading regime by binary and hypergeometric distribution functions.Finally, a comprehensive review of the xenon NMR literature, including previous optical pumping studies, is provided.; ; "

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Section: Temperature Dependencescontrasting

confidence: 52%

Optical pumping and xenon NMR

Raftery¹

1991

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“…While the analogous competition in the bulk fluid produces nonmonotonic behavior, 39 in zeolites the shift generally decreases monotonically with increasing temperature. 3 The simulations required to study the effect of Xe-O interaction on the zero loading shift are done at infinite dilution.…”

Section: 2b Contribution Of Xe-o Interaction To the 129 Xe Chemicmentioning

confidence: 91%

“…Recently Jameson et al [20][21][22][23] have achieved very good comparison between calculated and experimental shifts for Xe in NaA using grand canonical ensemble simulations with shielding functions for Xe derived from ab initio quantum mechanical calculations of 39 Ar in the presence of various atoms. Their model provides the first quantitative interpretation of the 129 Xe chemical shift in zeolite A.…”

Section: Introductionmentioning

confidence: 98%

Comparison of the ¹²⁹Xe NMR Chemical Shift with Simulation in Zeolite Y

1996

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We report quantitative agreement between Monte Carlo simulation and the experimental NMR chemical shift of 129 Xe adsorbed in the supercages of zeolite Y. This agreement supports previous assertions, originating from Ripmeester and Fraissard, that the Xe shift can in principle provide a sensitive measure of the structure imposed on Xe by the three-dimensional potential field provided by the crystal structure of the zeolite. Up to a loading of 7 Xe/cage at 300 K, we verify that the linear rise of shift with loading is due solely to Xe-Xe interaction. We also find excellent agreement at 144 K between simulation and the nonlinear experimental data of Cheung et al. The nonlinear dependence of shift on loading arises both from repulsive Xe-Xe and from repulsive Xe-O interactions. Finally we verify that the effect of temperature on the shift at zero loading can be related to the change of Xe-O pair correlation function at short separations.

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“…It has been found experimentally as in the present case (figure) that at a constant temperature, chemical shifts for different magnetic nuclei [1][2][3][4][5][6][7] vary linearly with the density of the gas at low to moderate pressures within experimental errors. This implies that one can write In a binary gas mixture with a mole fraction x of the solute (containing the magnetic nucleus under observation) and mole fraction (1-x) of the solvent, al is a function of x and is given by [2] al(…”

Section: Resultsmentioning

confidence: 80%

Pressure dependence of¹H and¹⁹F chemical shifts in 1,1-difluoroethylene gas and in gaseous mixtures

Singh

Mohanty

1983

Molecular Physics

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We have measured the chemical shifts, 8, and 'second virial shielding coefficient ', al, for gaseous 1,1-difluoroethylene and its mixture with other gases at varying pressures (~ 10-45 atmospheres). The 8 vs p (density) plot for 1H and 19F resonances is found to be linear within the pressure range studied. The sign of ~1 is negative. The influence of perturbers on 8 and a 1 is in the following order : Xe > SF~ > Kr> SiFa > CH4 > CF4 (spherical top molecules) and C~H6 > C2H4 > HC1 > CO2 (non-spherical top molecules). These trends are true for polar and non-polar solutes.

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Temperature and Density Dependence of the Local Magnetic Field in Dense Xenon Gas

Cited by 34 publications

References 8 publications

Optical pumping and xenon NMR

Optical pumping and xenon NMR

Comparison of the ¹²⁹Xe NMR Chemical Shift with Simulation in Zeolite Y

Pressure dependence of¹H and¹⁹F chemical shifts in 1,1-difluoroethylene gas and in gaseous mixtures

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Temperature and Density Dependence of the Local Magnetic Field in Dense Xenon Gas

Cited by 34 publications

References 8 publications

Optical pumping and xenon NMR

Optical pumping and xenon NMR

Comparison of the 129Xe NMR Chemical Shift with Simulation in Zeolite Y

Pressure dependence of1H and19F chemical shifts in 1,1-difluoroethylene gas and in gaseous mixtures

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Product

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Comparison of the ¹²⁹Xe NMR Chemical Shift with Simulation in Zeolite Y

Pressure dependence of¹H and¹⁹F chemical shifts in 1,1-difluoroethylene gas and in gaseous mixtures