S. Pommeret - Academia.edu (original) (raw)

Papers by S. Pommeret

Research paper thumbnail of Micro-usinage par impulsions laser ultra-courtes

Le Journal de Physique IV, 2001

Resume: Ce travail pr&ente des resultats de micro-usinage femtoseconde, utilisant une chaine Tisa... more Resume: Ce travail pr&ente des resultats de micro-usinage femtoseconde, utilisant une chaine Tisaphir a 1 KHz. Le cas des m&aux est particulierement envisage' et les taux d'ablation par tir est determine dans le cas du cuivre (48 nm/tir) et de l'inox (29 nm/tir).

Research paper thumbnail of Coupling between molecular rotations and OH⋯O motions in liquid water: Theory and experiment

The Journal of Chemical Physics, 2002

A new theory is proposed to describe spectral effects of the coupling between molecular rotations... more A new theory is proposed to describe spectral effects of the coupling between molecular rotations and OH¯O motions in liquid water. The correlation function approach is employed together with a special type of development in which the coupling energy of these two motions is the expansion parameter. The isotropy of the liquid medium plays an essential role in this study. Based on this theory, a new infrared pump-probe experiment is described permitting a visualization of molecular rotations at subpicosecond time scales. Full curves relating the mean squared rotational angle and time, and not only the rotational relaxation time, are measured by this experiment. However, very short times where the incident pulses overlap must be avoided in this analysis. The lifetime of OH¯O bonds in water is rotation-limited.

Research paper thumbnail of Structure et dynamique de la liaison hydrogène dans l'eau confinée ou aux interfaces

International audienceLorsque de l'eau est confinée dans une cavité nanométrique, ses proprié... more International audienceLorsque de l'eau est confinée dans une cavité nanométrique, ses propriétés structurales et dynamiques sont modifiées par rapport à celles de l'eau dans le volume. Les propriétés de l'eau confinée dans des oxydes présentent un intérêt à la fois fondamental et pratique, mais l'état du réseau percolatif dans ces cavités rigides est mal connu. Jusqu'à présent, la majorité des résultats a été obtenue sur de l'eau confinée dans de la matière molle. Nous présenterons ici des résultats obtenus sur la structure et la dynamique de l'eau confinée dans des systèmes rigides comme les oxydes. Pour cela, la spectroscopie infrarouge est une technique de choix, que ce soit par la grande gamme spectrale qu'elle offre (de l'infrarouge lointain, qui permet d'étudier des modes collectifs, au moyen infrarouge avec l'étude de la bande d'élongation O-H), mais aussi par la possibilité de faire des études de spectroscopie d'absorption ...

Research paper thumbnail of Real Time Visualization of Atomic Motions in Dense Phases

Novel Approaches to the Structure and Dynamics of Liquids: Experiments, Theories and Simulations, 2004

Research paper thumbnail of Theoretical Analysis of Frequency-domain "single-shot" (FDSS) ultrafast spectroscopy

Single-shot" ultrafast spectroscopy based on the frequency encoding of transient absorbance kinet... more Single-shot" ultrafast spectroscopy based on the frequency encoding of transient absorbance kinetics using chirped probe pulses is analyzed theoretically. FDSS has an advantage over pump-probe spectroscopy in a situation where the "noise" is dominated by amplitude variations of the signal. Unlike "single-shot" techniques based on spatial encoding of the kinetics, no a priori knowledge of the excitation profile of the pump is needed. FDSS spectroscopy can be used for many types of samples, liquid or solid, including those comparable in thickness to the wavelength of the probe light. Another advantage is that due to the interference of quasimonochromatic components of the chirped probe pulse, an oscillation pattern near the origin of the FDSS kinetics emerges. This interference pattern is unique and can be used to determine the complex dielectric function of the photogenerated species.

Research paper thumbnail of Ab initio study of Cd?thiol complexes: application to the modelling of the metallothionein active siteElectronic supplementary information (ESI) available: 1. Computational method test. 2. Optimized geometries of cadmium?thiolate clusters. Table 1: Experimental and calculated bond lengths in CdCl...

Physical Chemistry Chemical Physics, 2003

ABSTRACT

Research paper thumbnail of Frequency-domain “single-shot” ultrafast transient absorption spectroscopy using chirped laser pulses

Journal of Applied Physics, 2004

The submitted manuscript has been created by the University of Chicago as Operator of Argonne Nat... more The submitted manuscript has been created by the University of Chicago as Operator of Argonne National Laboratory ("Argonne") under Contract No. W-31-109-ENG-38 with the U. S. Department of Energy. The U. S. Government retains for itself, and others acting on its behalf, a paid-up, nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government.

Research paper thumbnail of Time-Resolved Infrared Spectroscopy of Water. Relation between the OH Stretching Frequency and the OO Distance

Polish journal of chemistry

it is shown how infrared pump-probe spectroscopy can be used to measure sub picosecond variations... more it is shown how infrared pump-probe spectroscopy can be used to measure sub picosecond variations of the oxygen-oxygen distribution function in liquid water, A diluted solution HDO/D2O rather than pure H2O is considered to switch off resonant vibrational interactions between water molecules; the local structure remains unchanged in this substitution. The present study is limited to times superior to 100-200 fs. This permits to avoid problems generated by hard sphere type collisions between water molecules, as well as the interference between ultrafast pump and probe pulses. It is then shown that the Novak-Mikenda type relations between the OH stretching frequency and the OO distance largely survive when going from standard to ultrafast infrared spectroscopy. Moreover, the infrared pump-probe profiles of OH stretching bands closely parallel the oxygen-oxygen distribution functions in this time domain. Infrared pump-probe spectroscopy is thus a useful substitute of time-resolved X-ray...

Research paper thumbnail of A new theory of rotation-vibration coupling in liquid water

Nonlinear Optics: Materials, Fundamentals and Applications, 2002

ABSTRACT

Research paper thumbnail of <title>Solvated electron at the light of femtosecond laser interaction</title>

We report the experimental study of the ultra-fast modification of the dielectric function of pur... more We report the experimental study of the ultra-fast modification of the dielectric function of pure water by an intense femtosecond laser pulse. Using a time-resolved optical interferometric technique, we measured the variation of the phase shift, which is proportional to the modification of the real part of the refractive index, as well as the variation of the fringes contrast, proportional to the modification of the absorption coefficient. We first observe a positive phase shift due to Kerr effect and immediately followed a negative one. After 200 fs, the phase shift becomes positive and remains so for at least 3 ps. Using the simple Drude - Lorentz model, we interpret this evolution as the result of electron self-trapping.

Research paper thumbnail of Femtosecond spectroscopy of ultrafast reactions in aqueous media

Journal of Physics: Condensed Matter, 1990

ABSTRACT

Research paper thumbnail of Femtosecond Infrared and Visible Spectroscopy of Excess Electron in Neat Dimethylsulfide

Le Journal de Physique IV, 1991

Research paper thumbnail of Dynamics of Water Confined in Clay Minerals

The Journal of Physical Chemistry C, 2012

Research paper thumbnail of Syndrome d’Ehlers-Danlos (SED) type III (hypermobile): validation d’une échelle clinique somatosensorielle (ECSS-62), à propos de 626 cas

Bulletin de l'Académie Nationale de Médecine

Research paper thumbnail of Rôle de la charge de la sonde moléculaire sur la solvatation. Aspects statiques et dynamiques

Journal de Chimie Physique

ABSTRACT The solvent reorganisation around two molecular probes, LDS 751 and DCM, has been invest... more ABSTRACT The solvent reorganisation around two molecular probes, LDS 751 and DCM, has been investigated in methanol solution. The decrease of the mean frequency of the DCM fluorescence spectrum as a function of time shows a biexponential kinetics. The fast decay has a (175±100) fs time constant and the slow component (3,2±0,1) ps is identical to the value found in the case of LDS 751. These findings are discussed with reference to the charge distribution in the electronic states involved and to literature results concerning another solvent probe, the solvated electron generated by pulse radiolysis or by multiphotonic ionisation of methanol.

Research paper thumbnail of Ultrafast spectroscopic investigations of the relaxation dynamics of a new class of water-soluble Coumarins

AIP Conference Proceedings, 1996

ABSTRACT

Research paper thumbnail of Electron reactivity in aqueous media: A femtosecond investigation of the primary species

International Journal of Radiation Applications and Instrumentation. Part C. Radiation Physics and Chemistry, 1989

ABSTRACT

Research paper thumbnail of Femtosecond Dynamics of Single Electron Transfer in Aqueous Media and Mimetic Models of Bioaggregates

Water and Ions in Biomolecular Systems, 1990

Research paper thumbnail of Femtosecond Dynamics of Single Electron Transfer in Aqueous Media

Springer Series in Chemical Physics, 1990

Research paper thumbnail of Hydrogen/deuterium isotope effects on femtosecond electron reactivity in aqueous media

The Journal of Physical Chemistry, 1991

ABSTRACT The effects of isotope substitution on the primary steps of electron reactivity in aqueo... more ABSTRACT The effects of isotope substitution on the primary steps of electron reactivity in aqueous media have been investigated by using femtosecond near-infrared and visible spectroscopy. In neat deuterated water, a precursor of the hydrated electron has been identified. For both H2O and D2O, this localized state (e(prehyd)-) which absorbs in the infrared is distinct from the fully hydrated state (e(hyd-)). In neat D2O the dynamics of electron localization is slightly slower (9%) than in H2O; however, the lifetime of this transient electronic state (250 fs) remains similar to the analogue in light water. The absence of an H/D isotope effect on the electron hydration dynamics is confirmed in ionic aqueous media and in organized assemblies by using an anionic species (chloride ion) and a chromophore (phenothiazine), respectively, as the electron donor. In pure aqueous solutions, the changes due to isotope substitution are mainly observed during the early electron-radical pair recombination (e(hyd)- + X3O+, e(hyd)- + OX with X = H or D). The percentage of hydrated electrons involved in the fast recombination is increased in D2O. This moderate H/D isotope effect can be linked to a change in the initial spatial distribution of the electron and prototropic radicals. The analysis of the femtosecond kinetics provides evidence that the primary electron-radical pairs (e(hyd)-...X3O+, e(hyd)-...OX) execute a one-dimensional (1D) walk before undergoing recombination. The jump rate of the neutralization processes is found to be significantly influenced by H/D isotope substitution (0.45 x 10(12) s-1 in D2O and 0.83 x 10(12) s-1 in H2O). Moreover, the recombination dynamics in H2O and D2O, which have a time scale comparable to the H/D bond lifetime, suggest the existence of a dynamical protic solvent reorganization in the vicinity of hydrated electron during the electron-radical pair&#39;s neutralization.

Research paper thumbnail of Micro-usinage par impulsions laser ultra-courtes

Le Journal de Physique IV, 2001

Resume: Ce travail pr&ente des resultats de micro-usinage femtoseconde, utilisant une chaine Tisa... more Resume: Ce travail pr&ente des resultats de micro-usinage femtoseconde, utilisant une chaine Tisaphir a 1 KHz. Le cas des m&aux est particulierement envisage' et les taux d'ablation par tir est determine dans le cas du cuivre (48 nm/tir) et de l'inox (29 nm/tir).

Research paper thumbnail of Coupling between molecular rotations and OH⋯O motions in liquid water: Theory and experiment

The Journal of Chemical Physics, 2002

A new theory is proposed to describe spectral effects of the coupling between molecular rotations... more A new theory is proposed to describe spectral effects of the coupling between molecular rotations and OH¯O motions in liquid water. The correlation function approach is employed together with a special type of development in which the coupling energy of these two motions is the expansion parameter. The isotropy of the liquid medium plays an essential role in this study. Based on this theory, a new infrared pump-probe experiment is described permitting a visualization of molecular rotations at subpicosecond time scales. Full curves relating the mean squared rotational angle and time, and not only the rotational relaxation time, are measured by this experiment. However, very short times where the incident pulses overlap must be avoided in this analysis. The lifetime of OH¯O bonds in water is rotation-limited.

Research paper thumbnail of Structure et dynamique de la liaison hydrogène dans l'eau confinée ou aux interfaces

International audienceLorsque de l'eau est confinée dans une cavité nanométrique, ses proprié... more International audienceLorsque de l'eau est confinée dans une cavité nanométrique, ses propriétés structurales et dynamiques sont modifiées par rapport à celles de l'eau dans le volume. Les propriétés de l'eau confinée dans des oxydes présentent un intérêt à la fois fondamental et pratique, mais l'état du réseau percolatif dans ces cavités rigides est mal connu. Jusqu'à présent, la majorité des résultats a été obtenue sur de l'eau confinée dans de la matière molle. Nous présenterons ici des résultats obtenus sur la structure et la dynamique de l'eau confinée dans des systèmes rigides comme les oxydes. Pour cela, la spectroscopie infrarouge est une technique de choix, que ce soit par la grande gamme spectrale qu'elle offre (de l'infrarouge lointain, qui permet d'étudier des modes collectifs, au moyen infrarouge avec l'étude de la bande d'élongation O-H), mais aussi par la possibilité de faire des études de spectroscopie d'absorption ...

Research paper thumbnail of Real Time Visualization of Atomic Motions in Dense Phases

Novel Approaches to the Structure and Dynamics of Liquids: Experiments, Theories and Simulations, 2004

Research paper thumbnail of Theoretical Analysis of Frequency-domain "single-shot" (FDSS) ultrafast spectroscopy

Single-shot" ultrafast spectroscopy based on the frequency encoding of transient absorbance kinet... more Single-shot" ultrafast spectroscopy based on the frequency encoding of transient absorbance kinetics using chirped probe pulses is analyzed theoretically. FDSS has an advantage over pump-probe spectroscopy in a situation where the "noise" is dominated by amplitude variations of the signal. Unlike "single-shot" techniques based on spatial encoding of the kinetics, no a priori knowledge of the excitation profile of the pump is needed. FDSS spectroscopy can be used for many types of samples, liquid or solid, including those comparable in thickness to the wavelength of the probe light. Another advantage is that due to the interference of quasimonochromatic components of the chirped probe pulse, an oscillation pattern near the origin of the FDSS kinetics emerges. This interference pattern is unique and can be used to determine the complex dielectric function of the photogenerated species.

Research paper thumbnail of Ab initio study of Cd?thiol complexes: application to the modelling of the metallothionein active siteElectronic supplementary information (ESI) available: 1. Computational method test. 2. Optimized geometries of cadmium?thiolate clusters. Table 1: Experimental and calculated bond lengths in CdCl...

Physical Chemistry Chemical Physics, 2003

ABSTRACT

Research paper thumbnail of Frequency-domain “single-shot” ultrafast transient absorption spectroscopy using chirped laser pulses

Journal of Applied Physics, 2004

The submitted manuscript has been created by the University of Chicago as Operator of Argonne Nat... more The submitted manuscript has been created by the University of Chicago as Operator of Argonne National Laboratory ("Argonne") under Contract No. W-31-109-ENG-38 with the U. S. Department of Energy. The U. S. Government retains for itself, and others acting on its behalf, a paid-up, nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government.

Research paper thumbnail of Time-Resolved Infrared Spectroscopy of Water. Relation between the OH Stretching Frequency and the OO Distance

Polish journal of chemistry

it is shown how infrared pump-probe spectroscopy can be used to measure sub picosecond variations... more it is shown how infrared pump-probe spectroscopy can be used to measure sub picosecond variations of the oxygen-oxygen distribution function in liquid water, A diluted solution HDO/D2O rather than pure H2O is considered to switch off resonant vibrational interactions between water molecules; the local structure remains unchanged in this substitution. The present study is limited to times superior to 100-200 fs. This permits to avoid problems generated by hard sphere type collisions between water molecules, as well as the interference between ultrafast pump and probe pulses. It is then shown that the Novak-Mikenda type relations between the OH stretching frequency and the OO distance largely survive when going from standard to ultrafast infrared spectroscopy. Moreover, the infrared pump-probe profiles of OH stretching bands closely parallel the oxygen-oxygen distribution functions in this time domain. Infrared pump-probe spectroscopy is thus a useful substitute of time-resolved X-ray...

Research paper thumbnail of A new theory of rotation-vibration coupling in liquid water

Nonlinear Optics: Materials, Fundamentals and Applications, 2002

ABSTRACT

Research paper thumbnail of <title>Solvated electron at the light of femtosecond laser interaction</title>

We report the experimental study of the ultra-fast modification of the dielectric function of pur... more We report the experimental study of the ultra-fast modification of the dielectric function of pure water by an intense femtosecond laser pulse. Using a time-resolved optical interferometric technique, we measured the variation of the phase shift, which is proportional to the modification of the real part of the refractive index, as well as the variation of the fringes contrast, proportional to the modification of the absorption coefficient. We first observe a positive phase shift due to Kerr effect and immediately followed a negative one. After 200 fs, the phase shift becomes positive and remains so for at least 3 ps. Using the simple Drude - Lorentz model, we interpret this evolution as the result of electron self-trapping.

Research paper thumbnail of Femtosecond spectroscopy of ultrafast reactions in aqueous media

Journal of Physics: Condensed Matter, 1990

ABSTRACT

Research paper thumbnail of Femtosecond Infrared and Visible Spectroscopy of Excess Electron in Neat Dimethylsulfide

Le Journal de Physique IV, 1991

Research paper thumbnail of Dynamics of Water Confined in Clay Minerals

The Journal of Physical Chemistry C, 2012

Research paper thumbnail of Syndrome d’Ehlers-Danlos (SED) type III (hypermobile): validation d’une échelle clinique somatosensorielle (ECSS-62), à propos de 626 cas

Bulletin de l'Académie Nationale de Médecine

Research paper thumbnail of Rôle de la charge de la sonde moléculaire sur la solvatation. Aspects statiques et dynamiques

Journal de Chimie Physique

ABSTRACT The solvent reorganisation around two molecular probes, LDS 751 and DCM, has been invest... more ABSTRACT The solvent reorganisation around two molecular probes, LDS 751 and DCM, has been investigated in methanol solution. The decrease of the mean frequency of the DCM fluorescence spectrum as a function of time shows a biexponential kinetics. The fast decay has a (175±100) fs time constant and the slow component (3,2±0,1) ps is identical to the value found in the case of LDS 751. These findings are discussed with reference to the charge distribution in the electronic states involved and to literature results concerning another solvent probe, the solvated electron generated by pulse radiolysis or by multiphotonic ionisation of methanol.

Research paper thumbnail of Ultrafast spectroscopic investigations of the relaxation dynamics of a new class of water-soluble Coumarins

AIP Conference Proceedings, 1996

ABSTRACT

Research paper thumbnail of Electron reactivity in aqueous media: A femtosecond investigation of the primary species

International Journal of Radiation Applications and Instrumentation. Part C. Radiation Physics and Chemistry, 1989

ABSTRACT

Research paper thumbnail of Femtosecond Dynamics of Single Electron Transfer in Aqueous Media and Mimetic Models of Bioaggregates

Water and Ions in Biomolecular Systems, 1990

Research paper thumbnail of Femtosecond Dynamics of Single Electron Transfer in Aqueous Media

Springer Series in Chemical Physics, 1990

Research paper thumbnail of Hydrogen/deuterium isotope effects on femtosecond electron reactivity in aqueous media

The Journal of Physical Chemistry, 1991

ABSTRACT The effects of isotope substitution on the primary steps of electron reactivity in aqueo... more ABSTRACT The effects of isotope substitution on the primary steps of electron reactivity in aqueous media have been investigated by using femtosecond near-infrared and visible spectroscopy. In neat deuterated water, a precursor of the hydrated electron has been identified. For both H2O and D2O, this localized state (e(prehyd)-) which absorbs in the infrared is distinct from the fully hydrated state (e(hyd-)). In neat D2O the dynamics of electron localization is slightly slower (9%) than in H2O; however, the lifetime of this transient electronic state (250 fs) remains similar to the analogue in light water. The absence of an H/D isotope effect on the electron hydration dynamics is confirmed in ionic aqueous media and in organized assemblies by using an anionic species (chloride ion) and a chromophore (phenothiazine), respectively, as the electron donor. In pure aqueous solutions, the changes due to isotope substitution are mainly observed during the early electron-radical pair recombination (e(hyd)- + X3O+, e(hyd)- + OX with X = H or D). The percentage of hydrated electrons involved in the fast recombination is increased in D2O. This moderate H/D isotope effect can be linked to a change in the initial spatial distribution of the electron and prototropic radicals. The analysis of the femtosecond kinetics provides evidence that the primary electron-radical pairs (e(hyd)-...X3O+, e(hyd)-...OX) execute a one-dimensional (1D) walk before undergoing recombination. The jump rate of the neutralization processes is found to be significantly influenced by H/D isotope substitution (0.45 x 10(12) s-1 in D2O and 0.83 x 10(12) s-1 in H2O). Moreover, the recombination dynamics in H2O and D2O, which have a time scale comparable to the H/D bond lifetime, suggest the existence of a dynamical protic solvent reorganization in the vicinity of hydrated electron during the electron-radical pair&#39;s neutralization.