Yann Danten - Academia.edu (original) (raw)

Papers by Yann Danten

The Journal of Physical Chemistry A

into molecular subdomains contributions is presented and a software, DOCTRINE (atomic group Decom... more into molecular subdomains contributions is presented and a software, DOCTRINE (atomic group Decomposition Of the Charge TRansfer INdExes) for the implementation of this novel model has been coded. Although our method applies to any fuzzy or to any disjoint exhaustive partitioning of the real space, it is here applied using a definition of chemically relevant molecular subdomains based on the Atoms in Molecules Bader basins. This choice has the relevant advantage of associating intra or inter subdomain contributions to rigorously defined quantum objects, yet bearing a clear chemical meaning. Our method allows for a quantitative evaluation of the subdomain contributions to the charge transfer, the charge transfer excitation length and the dipole moment change upon excitation. All these global indexes may be obtained either from the electron density increment or the electron density depletion upon excitation. However, the subdomain contributions obtained from the two distributions generally differ, therefore allowing to distinguish whether the contribution to a given property of a given subdomain is dominated by one of the two distributions or if both are playing a significant role. As a toy system for the first application of our model, a typical [D−π−A, π = conjugated bridge] compound belonging to the merocyanine dyes family is selected, and the first four excited states of this compound in a strongly polar protic solvent and in a weakly polar solvent are thoroughly investigated.

The state of aggregation at room temperature of tert-butanol (TBH) and perfluoro tert-butanol (TB... more The state of aggregation at room temperature of tert-butanol (TBH) and perfluoro tert-butanol (TBF) liquid mixtures is assessed by vibrational spectroscopy (Raman and infrared) and X-ray diffraction and analyzed using density functional theory (DFT) and molecular dynamics (MD) simulations. It is shown that larger clusters (mostly tetramers) of TBH are destroyed upon dilution with TBF. Small oligomers, monomers, and mainly heterodimers are present at the equimolar concentration. At variance with slightly interacting solvents, the signature of hetero-oligomers is shown by the appearance of a new broad band detected in the infrared region. The same spectral observation is detected for mixtures of other hydrogenated alcohols (methanol and 1-butanol). The new infrared feature is unaffected by dilution in a polar solvent (CDCl3) in a high-concentration domain, allowing us to assign it to the signature of small hetero-oligomers. MD simulations are used to assess the nature of the species present in the mixture (monomers and small hetero-oligomers) and to follow the evolution of their population upon the dilution. Combining MD simulations with DFT calculations, the infrared spectral profile is successfully analyzed in equimolecular mixtures. This study shows that TBF is a structure breaker of hydrogen-bonded alcohol networks and that the TBF (donor)-TBH (acceptor) heterodimer is the dominant species in an extended range of concentration, centered in the vicinity of the equimolar fraction.

Http Www Theses Fr, 1992

On developpe un potentiel realiste entre l'halogene et la molecule aromatique capable de decr... more On developpe un potentiel realiste entre l'halogene et la molecule aromatique capable de decrire les forces intermoleculaires classiques en phase liquide de repulsion, de dispersion et electrostatiques et de prendre en compte les processus de polarisation et de transfert de charge dans les cas des systemes i#2-bz et i#2-py. L'accent est mis egalement sur les proprietes physiques des complexes a l'etat electronique fondamental en phase gazeuse. Les proprietes structurales et thermodynamiques sont calculees par dynamique moleculaire pour les solutions d'iode diluee dans le benzene et dans la pyridine. On s'interesse plus precisement aux effets engendres par la dissolution de l'iode dans ces solvants, mais aussi aux proprietes specifiques comme la presence eventuelle de complexes en solution. Dans l'affirmative, leur structure et leur concentration sont determinees. On analyse les profils de bande (i. R. L. ) des solutions i#2/bz et i#2/py simulee et on s'interesse plus particulierement aux differents types de mouvements moleculaires a l'origine de ces spectres. Notre etude met en evidence la presence d'un mecanisme d'induction de tres courte portee responsable de l'exces d'absorption provoquee par la dissolution de l'iode

Physical Chemistry Chemical Physics, 2020

Molecular modelling combined with electronic structure scrutinization may provide required insigh... more Molecular modelling combined with electronic structure scrutinization may provide required insights for addressing challenges with respect to the identification of redox-active targets usable as sustainable electrodes.

HAL (Le Centre pour la Communication Scientifique Directe), 2006

ABSTRACT

HAL (Le Centre pour la Communication Scientifique Directe), 2006

Collision- and Interaction-Induced Spectroscopy, 1995

Investigations of induced far infrared profiles of non polar neat liquids and solutions (Van der ... more Investigations of induced far infrared profiles of non polar neat liquids and solutions (Van der Waals and electron donor acceptor binary mixtures) are reported and critically analysed by a multitechnique approach in order to better assess the concept of complex. For neat liquids (benzene and its fluorinated derivatives), the rotational and translational collective diffusive processes affect the spectral density while the ‘packing’ of the molecules governs the short-time dynamic reflected in the α(ω) profiles. In Van der Waals mixtures (C6H6-C6F6), the departures of induced bandshapes (excess intensity) from those of the pure components, might be ascribed to the spectral ‘signature’ of complexes. Finally, in solutions of weak charge transfer complexes (I2-Bz), both electrostatic and charge transfer interactions are found to coexist playing a major role respectively in the long-time and short-time dynamical behaviour of the intermolecular interactions. We emphasise that the studies of the previous solutions are relevant in the context of vibrational spectroscopic investigations of reactive fluids.

The Journal of Physical Chemistry B, 1997

ABSTRACT

The Journal of Physical Chemistry A, 2004

Infrared spectroscopic measurements of the ν OD stretching vibration of dilute deuterated ethanol... more Infrared spectroscopic measurements of the ν OD stretching vibration of dilute deuterated ethanol in supercritical CO 2 have been performed and analyzed, via a theoretical model and ab initio calculations, to better understand the ethanol-CO 2 interaction. It was found that strongly attractive interactions, predominantly due to dispersion, dominate the stabilization energy between ethanol and CO 2. Differences between the observed and theoretically predicted spectral shifts indicate the presence of local density enhancements. The continued observation of these enhancements up to temperatures significantly greater than the critical one, T/T c g 1.3, suggests that ethanol is a strongly attractive solute for CO 2 , at least in the spatial vicinity of the OH functional group. This suggestion is also supported by an analysis of the local density enhancement factors, as extracted from IR and other spectroscopies, as well as by the ab initio calculations.

The Journal of Chemical Physics, 2000

Solutions of water very diluted (xw∼10−3 mf) in benzene and hexafluorobenzene have been investiga... more 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...

The Journal of Chemical Physics, 2005

Far-infrared (FIR) and mid-infrared (MIR) profiles of D2O infinitely dilute in supercritical CO2 ... more Far-infrared (FIR) and mid-infrared (MIR) profiles of D2O infinitely dilute in supercritical CO2 have been studied using molecular-dynamics simulations. For this purpose, we have proposed an intermolecular potential model taking implicitly into account electron donor-acceptor (EDA) interactions between water and CO2 evaluated from ab initio calculations of the intermolecular potential-energy surface (IPS). Interaction-induced dipole mechanisms have been also taken into account in addition to the water permanent dipole to evaluate the simulated FIR profiles of water and CO2 polarizable molecules. They were found to play a minor role in the genesis of the FIR profiles of water/CO2 under supercritical conditions. The analysis of the reorientational dynamics of D2O shows that the rotational dynamics of water is weakly anisotropic due to the EDA interactions which affect more specifically the reorientational motions of the C2 symmetry axis of solute. These results have been used to asses...

The Journal of Chemical Physics, 2005

Raman scattering combined with near- and midinfrared absorption spectroscopies was used to invest... more Raman scattering combined with near- and midinfrared absorption spectroscopies was used to investigate the evolution of the local order in the water rich phase of water-CO2 mixtures under isobaric heating (T=40–360°C,P=250bars). The quantitative analysis of the spectra shows that tetramers and larger oligomers are the main constituents of water at moderate temperatures below 80 °C. As the temperature increases, the dimer and trimer concentrations considerably increase at the expense of larger oligomers. Finally, water dimers are predominant at the highest temperature investigated close to the temperature of total miscibility of the mixture (T=366°C,P=250bars). This result is consistent with our previous investigation [R. Oparin T. Tassaing, Y. Danten, and M. Besnard, J. Chem. Phys. 120, 10691 (2004)] on water dissolved in the CO2 rich phase where we found that close to the temperature of total miscibility water also exists mainly under dimeric form. The current study combined with t...

The Journal of Chemical Physics, 2001

This paper is devoted to an investigation of the local order in hexafluorobenzene by neutron diff... more This paper is devoted to an investigation of the local order in hexafluorobenzene by neutron diffraction and molecular-dynamics simulations. Experimentally, the fluid has been studied under isobaric (P∼16 MPa) and isothermal (T∼573 K) conditions in a broad density domain ranging from the liquid value (ρ∼1600 kg m−3) down to typical densities on the supercritical domain (ρ∼60 kg m−3). It is found that the translational ordering, which is characterized by two well defined shells of neighboring molecules at ambient conditions, is gradually weakened and extends only to the first shell as the density decreases in the supercritical domain. This behavior is in full agreement with the general trend reported for the positional ordering in our previous investigations for some cyclic molecules. In marked contrast, the short range orientational ordering existing in the first shell of molecule is almost preserved. It is found that parallel and perpendicular configurations of a pair of neighborin...

The journal of physical chemistry. A, 2007

The polarized IVV and depolarized IVH Raman profiles of the Fermi dyad (1285 cm(-1) and 1388 cm(-... more The polarized IVV and depolarized IVH Raman profiles of the Fermi dyad (1285 cm(-1) and 1388 cm(-1)) of supercritical (SC) CO2 have been measured along the isotherms 307, 309, 313, and 323 K in the reduced density range 0.04<rho*=rho/rhoC<2.04 (rhoC is the critical density). A band shape analysis of the dyad component shows that each one can be decomposed in two well-defined Lorentzian profiles in all of the temperature and density ranges investigated. These profiles have been assigned with the transitions of CO2 probing two kinds of environments. In each dyad peak, the Lorentzian profiles centered at higher frequency is associated with CO2 interacting through usual Van der Waals interactions with its nearest neighbors. The Lorentzian profiles centered at lower frequency in each dyad peak have been related to the transition of CO2 involved in a transient (CO2)2 dimer. The evolution with the density of the band center positions and bandwidths of the Lorentzian profiles shaping ...

The journal of physical chemistry. A, Jan 26, 2009

We have investigated water highly diluted in 1-alkyl-3-methyl imidazolium ionic liquids (ILs) wit... more We have investigated water highly diluted in 1-alkyl-3-methyl imidazolium ionic liquids (ILs) with hexafluorophosphate {PF(6)(-)} and tetrafluoroborate {BF(4)(-)} anions using vibrational spectroscopic measurements in the nu(OH) spectral domain of water (3600-3800 cm(-1)) and DFT calculations. The measured profiles exhibit two well-defined bands at coinciding vibrational transitions assigned with the nu(1) symmetric and nu(3) antisymmetric OH stretching modes of monodispersed water. The local organization and the vibrational spectra of water diluted in ILs have been assessed by DFT calculations (using the B3LYP functional and 6-31+G** basis set). We show that the predicted structures of water interacting (minimally) with two anions in nearly "symmetric" structures of type (A...H-O-H...A) lead to spectral features consistent with the previous spectroscopic observations as well as with those reported here. We emphasize the role of the non additive interaction forces (especia...

Chemical Physics Letters, 2005

The I VV and I HV Raman profiles of the m 2 bending mode of CO 2 diluted in acetone and in ethano... more The I VV and I HV Raman profiles of the m 2 bending mode of CO 2 diluted in acetone and in ethanol have been measured at pressures up to 10 MPa at 313 K. Upon the addition of CO 2 , the spectra exhibit a new polarised band interpreted as the spectral signature of transient electron donor-acceptor complexes formed between CO 2 and acetone or ethanol. This band is assigned to the lower frequency m ð1Þ 2 component of the bending mode after the degeneracy removal predicted in our previous work.

Chemical Physics Letters, 2000

The local ordering in 1,3,5-trifluorobenzene has been investigated under isothermal and isobaric ... more The local ordering in 1,3,5-trifluorobenzene has been investigated under isothermal and isobaric conditions from the liquid to the supercritical domain using neutron diffraction and molecular dynamics simulation. The short-range local ordering existing at ambient conditions involving dimers in which the molecules are in a parallel stacked configuration, is Ž. progressively weakened at the isobaric condition P s 16 MPa upon increasing the temperature up to 573 K. Under Ž. Ž. isothermal conditions 573 K and as the density goes down to about r s rrr s 0.43 reduced density , although the r c Ž orientational ordering reaches in the fluid a more random distribution, dimers are still present two thirds of the proportion. estimated at ambient conditions. q 2000 Published by Elsevier Science B.V.

The Journal of Physical Chemistry A

The Journal of Physical Chemistry A

into molecular subdomains contributions is presented and a software, DOCTRINE (atomic group Decom... more into molecular subdomains contributions is presented and a software, DOCTRINE (atomic group Decomposition Of the Charge TRansfer INdExes) for the implementation of this novel model has been coded. Although our method applies to any fuzzy or to any disjoint exhaustive partitioning of the real space, it is here applied using a definition of chemically relevant molecular subdomains based on the Atoms in Molecules Bader basins. This choice has the relevant advantage of associating intra or inter subdomain contributions to rigorously defined quantum objects, yet bearing a clear chemical meaning. Our method allows for a quantitative evaluation of the subdomain contributions to the charge transfer, the charge transfer excitation length and the dipole moment change upon excitation. All these global indexes may be obtained either from the electron density increment or the electron density depletion upon excitation. However, the subdomain contributions obtained from the two distributions generally differ, therefore allowing to distinguish whether the contribution to a given property of a given subdomain is dominated by one of the two distributions or if both are playing a significant role. As a toy system for the first application of our model, a typical [D−π−A, π = conjugated bridge] compound belonging to the merocyanine dyes family is selected, and the first four excited states of this compound in a strongly polar protic solvent and in a weakly polar solvent are thoroughly investigated.

The state of aggregation at room temperature of tert-butanol (TBH) and perfluoro tert-butanol (TB... more The state of aggregation at room temperature of tert-butanol (TBH) and perfluoro tert-butanol (TBF) liquid mixtures is assessed by vibrational spectroscopy (Raman and infrared) and X-ray diffraction and analyzed using density functional theory (DFT) and molecular dynamics (MD) simulations. It is shown that larger clusters (mostly tetramers) of TBH are destroyed upon dilution with TBF. Small oligomers, monomers, and mainly heterodimers are present at the equimolar concentration. At variance with slightly interacting solvents, the signature of hetero-oligomers is shown by the appearance of a new broad band detected in the infrared region. The same spectral observation is detected for mixtures of other hydrogenated alcohols (methanol and 1-butanol). The new infrared feature is unaffected by dilution in a polar solvent (CDCl3) in a high-concentration domain, allowing us to assign it to the signature of small hetero-oligomers. MD simulations are used to assess the nature of the species present in the mixture (monomers and small hetero-oligomers) and to follow the evolution of their population upon the dilution. Combining MD simulations with DFT calculations, the infrared spectral profile is successfully analyzed in equimolecular mixtures. This study shows that TBF is a structure breaker of hydrogen-bonded alcohol networks and that the TBF (donor)-TBH (acceptor) heterodimer is the dominant species in an extended range of concentration, centered in the vicinity of the equimolar fraction.

Http Www Theses Fr, 1992

On developpe un potentiel realiste entre l'halogene et la molecule aromatique capable de decr... more On developpe un potentiel realiste entre l'halogene et la molecule aromatique capable de decrire les forces intermoleculaires classiques en phase liquide de repulsion, de dispersion et electrostatiques et de prendre en compte les processus de polarisation et de transfert de charge dans les cas des systemes i#2-bz et i#2-py. L'accent est mis egalement sur les proprietes physiques des complexes a l'etat electronique fondamental en phase gazeuse. Les proprietes structurales et thermodynamiques sont calculees par dynamique moleculaire pour les solutions d'iode diluee dans le benzene et dans la pyridine. On s'interesse plus precisement aux effets engendres par la dissolution de l'iode dans ces solvants, mais aussi aux proprietes specifiques comme la presence eventuelle de complexes en solution. Dans l'affirmative, leur structure et leur concentration sont determinees. On analyse les profils de bande (i. R. L. ) des solutions i#2/bz et i#2/py simulee et on s'interesse plus particulierement aux differents types de mouvements moleculaires a l'origine de ces spectres. Notre etude met en evidence la presence d'un mecanisme d'induction de tres courte portee responsable de l'exces d'absorption provoquee par la dissolution de l'iode

Physical Chemistry Chemical Physics, 2020

Molecular modelling combined with electronic structure scrutinization may provide required insigh... more Molecular modelling combined with electronic structure scrutinization may provide required insights for addressing challenges with respect to the identification of redox-active targets usable as sustainable electrodes.

HAL (Le Centre pour la Communication Scientifique Directe), 2006

ABSTRACT

HAL (Le Centre pour la Communication Scientifique Directe), 2006

Collision- and Interaction-Induced Spectroscopy, 1995

Investigations of induced far infrared profiles of non polar neat liquids and solutions (Van der ... more Investigations of induced far infrared profiles of non polar neat liquids and solutions (Van der Waals and electron donor acceptor binary mixtures) are reported and critically analysed by a multitechnique approach in order to better assess the concept of complex. For neat liquids (benzene and its fluorinated derivatives), the rotational and translational collective diffusive processes affect the spectral density while the ‘packing’ of the molecules governs the short-time dynamic reflected in the α(ω) profiles. In Van der Waals mixtures (C6H6-C6F6), the departures of induced bandshapes (excess intensity) from those of the pure components, might be ascribed to the spectral ‘signature’ of complexes. Finally, in solutions of weak charge transfer complexes (I2-Bz), both electrostatic and charge transfer interactions are found to coexist playing a major role respectively in the long-time and short-time dynamical behaviour of the intermolecular interactions. We emphasise that the studies of the previous solutions are relevant in the context of vibrational spectroscopic investigations of reactive fluids.

The Journal of Physical Chemistry B, 1997

ABSTRACT

The Journal of Physical Chemistry A, 2004

Infrared spectroscopic measurements of the ν OD stretching vibration of dilute deuterated ethanol... more Infrared spectroscopic measurements of the ν OD stretching vibration of dilute deuterated ethanol in supercritical CO 2 have been performed and analyzed, via a theoretical model and ab initio calculations, to better understand the ethanol-CO 2 interaction. It was found that strongly attractive interactions, predominantly due to dispersion, dominate the stabilization energy between ethanol and CO 2. Differences between the observed and theoretically predicted spectral shifts indicate the presence of local density enhancements. The continued observation of these enhancements up to temperatures significantly greater than the critical one, T/T c g 1.3, suggests that ethanol is a strongly attractive solute for CO 2 , at least in the spatial vicinity of the OH functional group. This suggestion is also supported by an analysis of the local density enhancement factors, as extracted from IR and other spectroscopies, as well as by the ab initio calculations.

The Journal of Chemical Physics, 2000

Solutions of water very diluted (xw∼10−3 mf) in benzene and hexafluorobenzene have been investiga... more 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...

The Journal of Chemical Physics, 2005

Far-infrared (FIR) and mid-infrared (MIR) profiles of D2O infinitely dilute in supercritical CO2 ... more Far-infrared (FIR) and mid-infrared (MIR) profiles of D2O infinitely dilute in supercritical CO2 have been studied using molecular-dynamics simulations. For this purpose, we have proposed an intermolecular potential model taking implicitly into account electron donor-acceptor (EDA) interactions between water and CO2 evaluated from ab initio calculations of the intermolecular potential-energy surface (IPS). Interaction-induced dipole mechanisms have been also taken into account in addition to the water permanent dipole to evaluate the simulated FIR profiles of water and CO2 polarizable molecules. They were found to play a minor role in the genesis of the FIR profiles of water/CO2 under supercritical conditions. The analysis of the reorientational dynamics of D2O shows that the rotational dynamics of water is weakly anisotropic due to the EDA interactions which affect more specifically the reorientational motions of the C2 symmetry axis of solute. These results have been used to asses...

The Journal of Chemical Physics, 2005

Raman scattering combined with near- and midinfrared absorption spectroscopies was used to invest... more Raman scattering combined with near- and midinfrared absorption spectroscopies was used to investigate the evolution of the local order in the water rich phase of water-CO2 mixtures under isobaric heating (T=40–360°C,P=250bars). The quantitative analysis of the spectra shows that tetramers and larger oligomers are the main constituents of water at moderate temperatures below 80 °C. As the temperature increases, the dimer and trimer concentrations considerably increase at the expense of larger oligomers. Finally, water dimers are predominant at the highest temperature investigated close to the temperature of total miscibility of the mixture (T=366°C,P=250bars). This result is consistent with our previous investigation [R. Oparin T. Tassaing, Y. Danten, and M. Besnard, J. Chem. Phys. 120, 10691 (2004)] on water dissolved in the CO2 rich phase where we found that close to the temperature of total miscibility water also exists mainly under dimeric form. The current study combined with t...

The Journal of Chemical Physics, 2001

This paper is devoted to an investigation of the local order in hexafluorobenzene by neutron diff... more This paper is devoted to an investigation of the local order in hexafluorobenzene by neutron diffraction and molecular-dynamics simulations. Experimentally, the fluid has been studied under isobaric (P∼16 MPa) and isothermal (T∼573 K) conditions in a broad density domain ranging from the liquid value (ρ∼1600 kg m−3) down to typical densities on the supercritical domain (ρ∼60 kg m−3). It is found that the translational ordering, which is characterized by two well defined shells of neighboring molecules at ambient conditions, is gradually weakened and extends only to the first shell as the density decreases in the supercritical domain. This behavior is in full agreement with the general trend reported for the positional ordering in our previous investigations for some cyclic molecules. In marked contrast, the short range orientational ordering existing in the first shell of molecule is almost preserved. It is found that parallel and perpendicular configurations of a pair of neighborin...

The journal of physical chemistry. A, 2007

The polarized IVV and depolarized IVH Raman profiles of the Fermi dyad (1285 cm(-1) and 1388 cm(-... more The polarized IVV and depolarized IVH Raman profiles of the Fermi dyad (1285 cm(-1) and 1388 cm(-1)) of supercritical (SC) CO2 have been measured along the isotherms 307, 309, 313, and 323 K in the reduced density range 0.04<rho*=rho/rhoC<2.04 (rhoC is the critical density). A band shape analysis of the dyad component shows that each one can be decomposed in two well-defined Lorentzian profiles in all of the temperature and density ranges investigated. These profiles have been assigned with the transitions of CO2 probing two kinds of environments. In each dyad peak, the Lorentzian profiles centered at higher frequency is associated with CO2 interacting through usual Van der Waals interactions with its nearest neighbors. The Lorentzian profiles centered at lower frequency in each dyad peak have been related to the transition of CO2 involved in a transient (CO2)2 dimer. The evolution with the density of the band center positions and bandwidths of the Lorentzian profiles shaping ...

The journal of physical chemistry. A, Jan 26, 2009

We have investigated water highly diluted in 1-alkyl-3-methyl imidazolium ionic liquids (ILs) wit... more We have investigated water highly diluted in 1-alkyl-3-methyl imidazolium ionic liquids (ILs) with hexafluorophosphate {PF(6)(-)} and tetrafluoroborate {BF(4)(-)} anions using vibrational spectroscopic measurements in the nu(OH) spectral domain of water (3600-3800 cm(-1)) and DFT calculations. The measured profiles exhibit two well-defined bands at coinciding vibrational transitions assigned with the nu(1) symmetric and nu(3) antisymmetric OH stretching modes of monodispersed water. The local organization and the vibrational spectra of water diluted in ILs have been assessed by DFT calculations (using the B3LYP functional and 6-31+G** basis set). We show that the predicted structures of water interacting (minimally) with two anions in nearly "symmetric" structures of type (A...H-O-H...A) lead to spectral features consistent with the previous spectroscopic observations as well as with those reported here. We emphasize the role of the non additive interaction forces (especia...

Chemical Physics Letters, 2005

The I VV and I HV Raman profiles of the m 2 bending mode of CO 2 diluted in acetone and in ethano... more The I VV and I HV Raman profiles of the m 2 bending mode of CO 2 diluted in acetone and in ethanol have been measured at pressures up to 10 MPa at 313 K. Upon the addition of CO 2 , the spectra exhibit a new polarised band interpreted as the spectral signature of transient electron donor-acceptor complexes formed between CO 2 and acetone or ethanol. This band is assigned to the lower frequency m ð1Þ 2 component of the bending mode after the degeneracy removal predicted in our previous work.

Chemical Physics Letters, 2000

The local ordering in 1,3,5-trifluorobenzene has been investigated under isothermal and isobaric ... more The local ordering in 1,3,5-trifluorobenzene has been investigated under isothermal and isobaric conditions from the liquid to the supercritical domain using neutron diffraction and molecular dynamics simulation. The short-range local ordering existing at ambient conditions involving dimers in which the molecules are in a parallel stacked configuration, is Ž. progressively weakened at the isobaric condition P s 16 MPa upon increasing the temperature up to 573 K. Under Ž. Ž. isothermal conditions 573 K and as the density goes down to about r s rrr s 0.43 reduced density , although the r c Ž orientational ordering reaches in the fluid a more random distribution, dimers are still present two thirds of the proportion. estimated at ambient conditions. q 2000 Published by Elsevier Science B.V.

The Journal of Physical Chemistry A