The Experts below are selected from a list of 237 Experts worldwide ranked by ideXlab platform
M Besnard - One of the best experts on this subject based on the ideXlab platform.
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transient complex formation in co2 Hexafluorobenzene mixtures a combined raman and ab initio investigation
Journal of Physical Chemistry A, 2009Co-Authors: M Besnard, Isabel M Cabaco, Y DantenAbstract:The polarized and depolarized Raman spectra of CO2 in binary mixtures with Hexafluorobenzene have been measured in the dense phase along the isotherm 313 K as a function of concentration (0.03−0.7 molar fraction in CO2) by varying the pressure (0.5−6.2 MPa). Experimental observations in the ν2 bending region, in the ν1−2ν2 Fermi resonance dyad, and in the spectral domain between the Fermi dyad peaks on CO2 are reported. These results are discussed in comparison with those obtained in previous studies on CO2−C6H6 and CO2−acetone mixtures. We conclude in agreement with previous investigations that CO2 molecules can probe two environments. In one of them carbon dioxide interacts “specifically” with Hexafluorobenzene molecules to form a transient heterodimer, whereas in the other environment CO2 interacts “nonspecifically” with its neighbors. New ab initio calculations reported here allow rationalizing most of the experimental results. However, the observation of weak spectral features (bending mode and Fermi...
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dynamics of solitary water in benzene and Hexafluorobenzene an infrared and raman study
Journal of Chemical Physics, 2000Co-Authors: M Besnard, Y Danten, Thierry TassaingAbstract:Solutions of water very diluted (xw∼10−3 mf) in benzene and Hexafluorobenzene have been investigated using vibrational spectroscopy. In these two solvents, it was found that water is essentially in its monomeric form. The band-shape analysis of the infrared and Raman profiles associated with the symmetric v1 and antisymmetric v3 stretching vibrations of the water molecule in benzenic compounds has been performed and compared with the spectral results obtained for water diluted in liquid CCl4, considered here as the standard “inert” solvent. It is found that the reorientational motions of water around its different axes are always more hindered in benzene and Hexafluorobenzene than in liquid CCl4. Moreover, the reorientational motion of the main symmetry axis (z) of water is more hindered than that of the y-axis (in the molecular plane). Although the rotational behavior of water appears similar in both aromatic solvents, the shifts in the vibrational frequencies and the change in the vibrational intensitie...
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on the nature of the water Hexafluorobenzene interaction
Journal of Physical Chemistry A, 1999Co-Authors: Y Danten, Thierry Tassaing, M BesnardAbstract:The interaction between water and Hexafluorobenzene is discussed in light of an ab initio study. It is found that a dimer is formed with a binding energy of about −2 kcal/mol, with a geometry such ...
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structural investigations of liquid binary mixtures neutron diffraction and molecular dynamics studies of benzene Hexafluorobenzene and 1 3 5 trifluorobenzene
Journal of Physical Chemistry B, 1998Co-Authors: Isabel M Cabaco, Y Danten, M Besnard, Yves Guissani, Bertrand GuillotAbstract:The local structure in benzene-1,3,5-trifluorobenzene (BT), Hexafluorobenzene-1,3,5-trifluorobenzene (HT), and benzene- Hexafluorobenzene (BH) equimolar mixtures has been investigated by neutron di...
Y Danten - One of the best experts on this subject based on the ideXlab platform.
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transient complex formation in co2 Hexafluorobenzene mixtures a combined raman and ab initio investigation
Journal of Physical Chemistry A, 2009Co-Authors: M Besnard, Isabel M Cabaco, Y DantenAbstract:The polarized and depolarized Raman spectra of CO2 in binary mixtures with Hexafluorobenzene have been measured in the dense phase along the isotherm 313 K as a function of concentration (0.03−0.7 molar fraction in CO2) by varying the pressure (0.5−6.2 MPa). Experimental observations in the ν2 bending region, in the ν1−2ν2 Fermi resonance dyad, and in the spectral domain between the Fermi dyad peaks on CO2 are reported. These results are discussed in comparison with those obtained in previous studies on CO2−C6H6 and CO2−acetone mixtures. We conclude in agreement with previous investigations that CO2 molecules can probe two environments. In one of them carbon dioxide interacts “specifically” with Hexafluorobenzene molecules to form a transient heterodimer, whereas in the other environment CO2 interacts “nonspecifically” with its neighbors. New ab initio calculations reported here allow rationalizing most of the experimental results. However, the observation of weak spectral features (bending mode and Fermi...
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dynamics of solitary water in benzene and Hexafluorobenzene an infrared and raman study
Journal of Chemical Physics, 2000Co-Authors: M Besnard, Y Danten, Thierry TassaingAbstract:Solutions of water very diluted (xw∼10−3 mf) in benzene and Hexafluorobenzene have been investigated using vibrational spectroscopy. In these two solvents, it was found that water is essentially in its monomeric form. The band-shape analysis of the infrared and Raman profiles associated with the symmetric v1 and antisymmetric v3 stretching vibrations of the water molecule in benzenic compounds has been performed and compared with the spectral results obtained for water diluted in liquid CCl4, considered here as the standard “inert” solvent. It is found that the reorientational motions of water around its different axes are always more hindered in benzene and Hexafluorobenzene than in liquid CCl4. Moreover, the reorientational motion of the main symmetry axis (z) of water is more hindered than that of the y-axis (in the molecular plane). Although the rotational behavior of water appears similar in both aromatic solvents, the shifts in the vibrational frequencies and the change in the vibrational intensitie...
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on the nature of the water Hexafluorobenzene interaction
Journal of Physical Chemistry A, 1999Co-Authors: Y Danten, Thierry Tassaing, M BesnardAbstract:The interaction between water and Hexafluorobenzene is discussed in light of an ab initio study. It is found that a dimer is formed with a binding energy of about −2 kcal/mol, with a geometry such ...
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structural investigations of liquid binary mixtures neutron diffraction and molecular dynamics studies of benzene Hexafluorobenzene and 1 3 5 trifluorobenzene
Journal of Physical Chemistry B, 1998Co-Authors: Isabel M Cabaco, Y Danten, M Besnard, Yves Guissani, Bertrand GuillotAbstract:The local structure in benzene-1,3,5-trifluorobenzene (BT), Hexafluorobenzene-1,3,5-trifluorobenzene (HT), and benzene- Hexafluorobenzene (BH) equimolar mixtures has been investigated by neutron di...
Thierry Tassaing - One of the best experts on this subject based on the ideXlab platform.
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dynamics of solitary water in benzene and Hexafluorobenzene an infrared and raman study
Journal of Chemical Physics, 2000Co-Authors: M Besnard, Y Danten, Thierry TassaingAbstract:Solutions of water very diluted (xw∼10−3 mf) in benzene and Hexafluorobenzene have been investigated using vibrational spectroscopy. In these two solvents, it was found that water is essentially in its monomeric form. The band-shape analysis of the infrared and Raman profiles associated with the symmetric v1 and antisymmetric v3 stretching vibrations of the water molecule in benzenic compounds has been performed and compared with the spectral results obtained for water diluted in liquid CCl4, considered here as the standard “inert” solvent. It is found that the reorientational motions of water around its different axes are always more hindered in benzene and Hexafluorobenzene than in liquid CCl4. Moreover, the reorientational motion of the main symmetry axis (z) of water is more hindered than that of the y-axis (in the molecular plane). Although the rotational behavior of water appears similar in both aromatic solvents, the shifts in the vibrational frequencies and the change in the vibrational intensitie...
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on the nature of the water Hexafluorobenzene interaction
Journal of Physical Chemistry A, 1999Co-Authors: Y Danten, Thierry Tassaing, M BesnardAbstract:The interaction between water and Hexafluorobenzene is discussed in light of an ab initio study. It is found that a dimer is formed with a binding energy of about −2 kcal/mol, with a geometry such ...
Peter P Antich - One of the best experts on this subject based on the ideXlab platform.
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regional tumor oxygen dynamics 19f pbsr epi of Hexafluorobenzene
Magnetic Resonance Imaging, 1997Co-Authors: Ralph P Mason, Sandeep Hunjan, Anca Constantinescu, Bruce R Barker, Peter P AntichAbstract:We demonstrate a novel approach to measuring regional tumor oxygen tension using 19F pulse burst saturation recovery echo planar imaging (EPI) relaxometry of Hexafluorobenzene. Hexafluorobenzene offers exceptional sensitivity to changes in oxygen tension, and has a single resonance making it ideal for imaging studies. By combining a pulse burst saturation recovery preparation sequence with EPI, the relaxation experiments were performed in ∼20 min facilitating measurements of dynamic changes in pO2 accompanying interventions. Direct intratumoral administration of Hexafluorobenzene permitted labeling of specific regions of interest, and imaging provided maps of pO2, confirming distinct intra tumoral heterogeneity. For a group of three Dunning prostate adenocarcinoma R3327-AT1 tumors interrogation of the central tumor region showed skewed pO2 distributions with considerable radiobiological hypoxia (∼90% voxels had pO2 15 torr. EPI allows the fate of individual voxels to be traced: upon altering the inspired gas to pure oxygen those voxels with baseline pO2 > 30 torr showed significant changes (p < 0.05), whereas those with pO2 < 16 torr showed minimal response. The precision of the measurements, together with the ability to simultaneously examine dynamic changes in multiple regions should provide a useful technique for investigating tumor hypoxia with respect to therapy.
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Hexafluorobenzene a sensitive 19f nmr indicator of tumor oxygenation
NMR in Biomedicine, 1996Co-Authors: Ralph P Mason, Watchara Rodbumrung, Peter P AntichAbstract:We have surveyed the sensitivity of the spin lattice relaxation rates of the 19F resonances of several perfluorocarbons to changes in oxygen tension and temperature. Hexafluorobenzene was found to exhibit exceptional sensitivity to changes in oxygen tension, and we have exploited this phenomenon to measure tumor oxygen tension following intratumoral injection. When 20 microliters hexaflourobenzene were injected they remained localized and the biodistribution was readily assessed on the basis of combined 1H and 19F three-dimensional MRI. Relaxation measurements indicated a typical baseline oxygen tension of 4.0 +/- 1.5 torr in the central region of a Dunning prostate R3327-AT1 tumor when the rat breathed 66% oxygen. Altering the inspired oxygen concentration to 100% produced a modest increase in pO2 (5.6 +/- 0.7 torr; p < 0.1). Significantly, the precision of these measurements should facilitate NMR investigations of radiobiological hypoxia. Intra-tumoral injection allowed measurements from regions not normally accessible to infused perfluorocarbons and provides an additional approach to measuring tumor oxygenation.
Jaime Wisniak - One of the best experts on this subject based on the ideXlab platform.
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the polyazeotropic behaviour of the benzene plus Hexafluorobenzene system revisited
The Journal of Chemical Thermodynamics, 2017Co-Authors: Hector Quinteroslama, Felix Llovell, Jaime WisniakAbstract:Abstract Polyazeotropy is a singular and elusive phenomenon in phase equilibria limited to very few mixtures, among which the benzene plus Hexafluorobenzene is the most noted. This particular system has been chosen to study the ability of the PC-SAFT, PPC-SAFT and soft-SAFT equations of state to describe the mechanisms of its phase equilibrium and the impact of specific molecular contributions such as the inclusion of a treatment for polarity. For this purpose, several parametric projections of the limiting conditions of the azeotropic phenomena, focused on the benzene plus Hexafluorobenzene mixture, have been built for uncovering the limitations and capabilities of the models. The results indicate that the polar contribution is at the heart of the complex behaviour of this system and is an indispensable factor for predicting its behaviour. However, it is impossible to find a single binary interaction coefficient capable of reproducing the mechanisms of the mixture and, consequently, a temperature-dependent binary interaction parameter is required to reach the qualitative and quantitative agreement at the whole range of conditions explored. Moreover, no substantial differences are obtained regardless of the reference function and chain contribution used for building a model for this binary system.
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double azeotropy in the benzene Hexafluorobenzene system
Journal of Chemical & Engineering Data, 1996Co-Authors: Antonio Aucejo, Juan B Monton, And Rosa Munoz, Jaime WisniakAbstract:Vapor−liquid equilibrium was measured for the benzene (1) + Hexafluorobenzene (2) system at 16 and 120 kPa. The system forms two azeotropes although its behavior is close to ideal. The compositions of the two azeotropes approach one another as the operating pressure is increased. The equilibrium data are thermodynamically consistent according to the point-to-point test of Fredenslund.