129Xe Nmr As A Probe Of Microporous Materials

1991 ◽  
Vol 233 ◽  
Author(s):  
John A. Ripmeester ◽  
Christopher I. Ratcliffe
Keyword(s):  
Phase Diagram ◽  
Chemical Shift ◽  
Gas Phase ◽  
Microporous Materials ◽  
129Xe Nmr ◽  
Large Pore ◽  
Microporous Solids ◽  
Interpretation Of Results

ABSTRACTIt is shown that the interpretation of 129Xe chemical shift measurements in microporous solids is not simple, and that considerable caution must be used both in the measurement and interpretation of results, especially for large pore systems. Nevertheless, useful information can be obtained on the phase diagram of xenon in pore systems, and on transport within the solid and between the solid and the gas phase.

Intermolecular Interactions of Xe Atoms Confined in One-dimensional Nanochannels of Tris(o-phenylenedioxy)cyclotriphosphazene as Studied by High-pressure 129Xe NMR

2003 ◽  
Vol 58 (12) ◽  
pp. 727-734 ◽  
Author(s):  
Hirokazu Kobayashi ◽  
Takahiro Ueda ◽  
Keisuke Miyakubo ◽  
Taro Eguchi
Keyword(s):  
High Pressure ◽  
Nmr Spectroscopy ◽  
Chemical Shift ◽  
Pressure Dependence ◽  
Average Distance ◽  
Chemical Shift Tensor ◽  
Axially Symmetric ◽  
One Dimensional ◽  
129Xe Nmr ◽  
The One

The pressure dependence of the 129Xe chemical shift tensor confined in the Tris(o-phenylenedioxy) cyclotriphosphazene (TPP) nanochannel was investigated by high-pressure 129Xe NMR spectroscopy. The observed 129Xe spectrum in the one-dimensional TPP nanochannel (0.45 nm in diameter) exhibits a powder pattern broadened by an axially symmetric chemical shift tensor. As the pressure increases from 0.02 to 7.0 MPa, a deshielding of 90 ppm is observed for the perpendicularcomponent of the chemical shift tensor δ⊥, whereas a deshielding of about 30 ppm is observed for the parallel one, δ‖. This suggests that the components of the chemical shift tensor, δ‖ and δ⊥, are mainly dominated by the Xe-wall and Xe-Xe interaction, respectively. Furthermore, the effect of helium, which is present along with xenon gas, on the 129Xe chemical shift is examined in detail. The average distance between the Xe atoms in the nanochannel is estimated to be 0.54 nm. This was found by using δ⊥ at the saturated pressure of xenon, and comparing the increment of the chemicalshift value in δ⊥ to that of a β -phenol/Xe compound.

scholarly journals Thermodynamic modeling of the Al-K system

2009 ◽  
Vol 45 (1) ◽  
pp. 89-93 ◽  
Author(s):  
Y. Du ◽  
X. Yuan ◽  
W. Sun ◽  
B. Hu
Keyword(s):  
Phase Diagram ◽  
Gas Phase ◽  
Thermodynamic Modeling ◽  
Phase Diagram Data ◽  
Ideal Gas ◽  
Monotectic Reaction ◽  
Present Calculation ◽  
Experimental Phase ◽  
Experimental Phase Diagram ◽  
Ideal Gas Model

A thermodynamic modeling for the Al-K system is conducted. The thermodynamic parameters for liquid, (Al), and (K) are evaluated by using the experimental phase diagram data from the literature. The gas phase is described with an ideal gas model. The calculated Al-K phase diagram agrees well with the experimental data. In particular, the observed monotectic reaction is well described by the present calculation.

Ab initio Conformational Analysis of Glutamic Acid, Chemical Shift Anisotropy and Population Studies

2003 ◽  
Vol 2003 (8) ◽  
pp. 454-456 ◽  
Author(s):  
M. Monajjemi ◽  
M.T. Azad ◽  
H.H. Haeri ◽  
K. Zare ◽  
Sh. Hamedani
Keyword(s):  
Chemical Shift ◽  
Conformational Analysis ◽  
Glutamic Acid ◽  
Gas Phase ◽  
Population Studies ◽  
Chemical Shift Anisotropy ◽  
High Energy ◽  
Stable Conformer ◽  
Rotational Angle ◽  
Radical Attack

We report on glutamic acid rotation and its stable conformer in gas phase. The calculations were performed by HF/6-31G* and B3lyp/6-31G* levels of theory. There is a pertubation in the population diagram of the C3 that shows nucleophilic or radical attack will probably occur at this site. This fact is confirmed by the charge distribution and CSA (chemical shift anisotropy) diagrams. The energies and the relative energies are given as a function of rotational angle. Also, low and high-energy barriers of N-H rotation computed at various level of theory have been obtained. Vibrational frequencies of the structure were done to verify the minima of the energy.

129Xe NMR in Polymers

1993 ◽  
Vol 66 (3) ◽  
pp. 455-461 ◽  
Author(s):  
J. B. Miller
Keyword(s):  
Chemical Shift ◽  
Amorphous Phase ◽  
Van Der Waals ◽  
Phase Morphology ◽  
Van Der Waals Interaction ◽  
Interaction Energies ◽  
Near Surface ◽  
129Xe Nmr ◽  
Spin Polarized ◽  
Bulk Polymers

Abstract Through the efforts of many researchers, 129Xe NMR has shown to be a sensitive probe of phase morphology in polymers, providing a unique means of investigating the amorphous phase of bulk polymers. Recently developed models of the 129Xe chemical shift in polymers open the possibility of measuring van der Waals' interaction energies and chain dimensions from xenon spectra. In most cases, the information obtained from 129Xe NMR pertains only to the amorphous phase of the polymer, even in semicrystalline systems. The use of spin-polarized xenon has opened the possibility of probing the surface and near surface regions of polymers.

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