Search

Your search keyword '"Jean-Michel Mestdagh"' showing total 72 results
Start Over Author "Jean-Michel Mestdagh"
72 results on '"Jean-Michel Mestdagh"'

3. Vacuum-Ultraviolet Absorption Spectrum of 3-Methoxyacrylonitrile

Author

M. Briant, Jean-Michel Mestdagh, Nelson de Oliveira, Marc-André Gaveau, Anja Röder, and Floriane Grollau

Subjects
Valence (chemistry), 010304 chemical physics, Spectrometer, Nitrile, Absorption spectroscopy, 010402 general chemistry, 01 natural sciences, Molecular physics, 0104 chemical sciences, symbols.namesake, chemistry.chemical_compound, chemistry, Ionization, 0103 physical sciences, Rydberg formula, symbols, Molecule, Physical and Theoretical Chemistry, Methyl group
Abstract

The high-resolution absorption spectrum of 3-methoxyacrylonitrile (3MAN) was measured between 5.27 and 12.59 eV using a synchrotron-based Fourier-transform spectrometer. It was related to an absolute absorption cross-section scale. Complementary calculations at the DFT-MRCI/aug-cc-pVTZ level of theory document the vertical transition energies and oscillator strengths toward the first 19 states of both the E and Z geometrical isomers of 3MAN. Comparisons with the experimental absorption spectrum reveal the similarities and differences between 3MAN, a bifunctional molecule, with acrylonitrile and methylvinylether, where only one functional group is present. As in acrylonitrile, several broad valence transitions were observed up to the ionization limit. They are likely associated with the extended π-system induced by the nitrile group but might also involve σσ* transitions close to the ionization limit. As in methylvinylether, Rydberg series converging to the ionization limit are absent. This is attributed to a difference in neutral and cationic geometry due to a 60° rotation of the methyl group.

Published
2020

4. Reaction Dynamics within a Cluster Environment

Author

Marc Briant, Jean-Michel Mestdagh, Marc-André Gaveau, Lionel Poisson, Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Dynamique Réactionnelle (DyR), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences Moléculaires d'Orsay (ISMO), and Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS]Physics [physics], [CHIM]Chemical Sciences, General Physics and Astronomy, Physical and Theoretical Chemistry
Abstract

International audience; This perspective article reviews experimental and theoretical works where rare gas clusters and helium nanodroplet are used as nanoreactor to investigate chemical dynamics in a solvent environment. A historical perspective is presented first, then specific considerations on the mobility of reactants within these reaction media. The dynamical response of pure clusters and nanodroplets to photoexcitation is shortly reviewed before examining the role of the cluster (or nanodroplet) degrees of freedom on the photodynamics of the guest atoms and molecules.

Published
2022

6. The role of spin-orbit coupling in the optical spectroscopy of atomic sodium isolated in solid xenon

Author

John G. McCaffrey, Claudine Crépin, P. de Pujo, Jean-Michel Mestdagh, Maryanne C. Ryan, Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Dynamique Réactionnelle (DyR), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Chemistry [Maynooth University], National University of Ireland Maynooth (Maynooth University), SYSIPHE, Institut des Sciences Moléculaires d'Orsay (ISMO), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010302 applied physics, Coupling constant, Coupling, Materials science, Physics and Astronomy (miscellaneous), [PHYS.PHYS.PHYS-ATM-PH]Physics [physics]/Physics [physics]/Atomic and Molecular Clusters [physics.atm-clus], General Physics and Astronomy, chemistry.chemical_element, Spin–orbit interaction, 01 natural sciences, Molecular physics, Xenon, chemistry, Vacancy defect, 0103 physical sciences, Atom, Absorption (chemistry), 010306 general physics, Spectroscopy
Abstract

Molecular dynamics calculations, based on the diatomics-in-molecules method, have been used to probe the manifestations of spin-orbit (SO) coupling in the experimental absorption bands of atomic sodium isolated in solid xenon. Inclusion of SO coupling of –320 cm−1 in spectral simulations of the 3 p 2 P ← 3 s 2 S transition leads to unequal band spacings which very closely match the asymmetrical bandshape observed for blue single vacancy (SV) site occupancy. This SO value, extracted in a previous MCD study, reveals the dramatic change in the effective SO coupling constant of the Na atom (from the gas phase value of +17 cm−1) in solid Xe when it is close to the 12 xenon atoms in the first surrounding sphere. In contrast, the symmetrical three-fold split band of the red tetra vacancy (TV) site in Na/Xe is not affected nearly as much by SO coupling. This reflects a greatly reduced “external heavy atom” effect when the 24 Xe atoms surrounding the Na atom in TV are located at greater distances. The contrasting behavior of sodium in the SV and TV sites suggests a strong dependence of the SO coupling strength on the Na–Xe distance.Molecular dynamics calculations, based on the diatomics-in-molecules method, have been used to probe the manifestations of spin-orbit (SO) coupling in the experimental absorption bands of atomic sodium isolated in solid xenon. Inclusion of SO coupling of –320 cm−1 in spectral simulations of the 3 p 2 P ← 3 s 2 S transition leads to unequal band spacings which very closely match the asymmetrical bandshape observed for blue single vacancy (SV) site occupancy. This SO value, extracted in a previous MCD study, reveals the dramatic change in the effective SO coupling constant of the Na atom (from the gas phase value of +17 cm−1) in solid Xe when it is close to the 12 xenon atoms in the first surrounding sphere. In contrast, the symmetrical three-fold split band of the red tetra vacancy (TV) site in Na/Xe is not affected nearly as much by SO coupling. This reflects a greatly reduced “external heavy atom” effect when the 24 Xe atoms surrounding the Na atom in TV are located at greater distances. The contra...

Published
2019

7. Time Resolved Observation of the Solvation Dynamics of a Rydberg Excited Molecule Deposited on an Argon Cluster -II: DABCO at Long Time Delays

Author

Jean-Michel Mestdagh, Slim Awali, Vincent Mazet, M. Briant, Marc-André Gaveau, Benoît Soep, Lionel Poisson, Unité d’Éude des Milieux Ionisés et Réactifs [Monastir] (EMIR), Institut Préparatoire aux Etudes d'Ingénieurs de Monastir (IPEIM), Université de Monastir - University of Monastir (UM)-Université de Monastir - University of Monastir (UM), Dynamique Réactionnelle (DyR), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences Moléculaires d'Orsay (ISMO), Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire des sciences de l'ingénieur, de l'informatique et de l'imagerie (ICube), Institut National des Sciences Appliquées - Strasbourg (INSA Strasbourg), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-École Nationale du Génie de l'Eau et de l'Environnement de Strasbourg (ENGEES)-Réseau nanophotonique et optique, Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Matériaux et nanosciences d'Alsace (FMNGE), Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), École Nationale du Génie de l'Eau et de l'Environnement de Strasbourg (ENGEES)-Université de Strasbourg (UNISTRA)-Institut National des Sciences Appliquées - Strasbourg (INSA Strasbourg), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut National de Recherche en Informatique et en Automatique (Inria)-Les Hôpitaux Universitaires de Strasbourg (HUS)-Centre National de la Recherche Scientifique (CNRS)-Matériaux et Nanosciences Grand-Est (MNGE), Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Réseau nanophotonique et optique, and Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010304 chemical physics, Relaxation (NMR), [PHYS.PHYS.PHYS-ATM-PH]Physics [physics]/Physics [physics]/Atomic and Molecular Clusters [physics.atm-clus], Solvation, Photoionization, DABCO, 010402 general chemistry, 01 natural sciences, Molecular physics, 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, chemistry.chemical_compound, symbols.namesake, chemistry, Excited state, 0103 physical sciences, Cluster (physics), Rydberg formula, symbols, Physics::Atomic and Molecular Clusters, Physics::Chemical Physics, Physical and Theoretical Chemistry, Anisotropy
Abstract

International audience; The real-time dynamics of DABCO–argon clusters is investigated in a femtosecond pump–probe experiment where the pump excites DABCO to the S1 state within the argon cluster. The probe operates by photoionization and documents the energy and angular distributions of the resulting photoelectrons. The present work complements a previous work from our group [Awali Phys. Chem. Chem. Phys., 2014, 16, 516−526] where this dynamics was probed at short time, up to 4 ps after the pump pulse. Here, the dynamics is followed up to 500 ps. A multiscale dynamics is observed. It includes a jump between two solvation sites (time scale 0.27 ps) followed by the relaxation of the solvation cage excess vibrational energy (time scale 14 ps) and then by that of DABCO (time scale >150 ps). Polarization anisotropy, double polarization, and angular anisotropy effects are reported also. They are interpreted (quantitatively for the former effect) in terms of decoherence of rotational alignment, driven by the overall rotation of the DABCO–argon clusters. A tomographic view of the DABCO excited orbital, provided by the double anisotropy effect, is discussed on a qualitative basis.

Published
2021

8. Excited State Dynamics of Isolated 6‐ and 8‐Hydroxyquinoline Molecules

Author

Lionel Poisson, Jean-Michel Mestdagh, Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Dynamique Réactionnelle (DyR), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), LUmière et MOlécules (LUMO), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), and Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Time constant, 02 engineering and technology, Conical intersection, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, Molecular physics, Atomic and Molecular Physics, and Optics, 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Ab initio quantum chemistry methods, Intramolecular force, Excited state, Femtosecond, Molecule, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], Physical and Theoretical Chemistry, 0210 nano-technology, Excitation
Abstract

International audience; The photoinduced dynamics of isolated n‐hydroxyquinoline (nHQ) molecules (n=6,8) was investigated in femtosecond pump‐probe experiments. A qualitative difference was found between 8HQ and 6HQ. After an initial rapid decay corresponding to the departure of the initial wavepacket out of the Franck‐Condon region of the excitation, the 8HQ probe signal decays to zero in 0.37 ps whereas a much longer time constant of 10.4 ps is observed in 6HQ. This interrogates on the role played by the intramolecular H‐bond N HO which is at play the 8HQ molecule. Ab‐initio were performed at the MCSCF/aug‐cc‐pVDZ level on the 8HQ molecule to help the discussion. A complex energy landscape was found, which includes a conical intersection.

Published
2020

9. High-resolution vacuum ultraviolet absorption spectra of 2,3- and 2,5-dihydrofuran

Author

M. Briant, Nelson de Oliveira, Floriane Grollau, Marc-André Gaveau, Laurent Nahon, Anja Röder, Guillaume Gallician, Jean-Michel Mestdagh, Department of Chemistry, University of Ottawa, 10 Marie Curie, Ottawa, Ontario, Canada KIN 6N5, University of Ottawa [Ottawa], Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), LUmière et MOlécules (LUMO), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Valence (chemistry), 010304 chemical physics, Absorption spectroscopy, Absorption cross section, General Physics and Astronomy, Propagator, 010402 general chemistry, 01 natural sciences, 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, symbols.namesake, 0103 physical sciences, Rydberg formula, symbols, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], Physical and Theoretical Chemistry, Ionization energy, Atomic physics, Excitation, Order of magnitude
Abstract

International audience; Using a synchrotron-based Fourier-transform spectrometer, the high-resolution absorption spectra of the C1-symmetric 2,3-dihydrofuran (23DHF) and C2v-symmetric 2,5-dihydrofuran (25DHF) have been measured from 5.5 eV to 9.4 eV with an absolute absorption cross section scale. Oscillator strengths and vertical excitation energies of the lowest 18 states have been computed using the average of the second- and third-order algebraic diagrammatic construction polarization propagator method and the equation-of-motion coupled-cluster method at the level of singles and doubles model. These show that the bright valence transitions of ππ*-character are embedded into Rydberg transitions, whose oscillator strengths are at least one order of magnitude lower. To account for intensity borrowing, the first broad valence transition between 5.5 eV and 6.8 eV was simulated using a nuclear ensemble, and the agreement between experiment and theory is excellent. Whereas 23DHF only exhibits one broad valence transition followed by d/f Rydberg series converging to the ionization energy, the absorption spectrum of 25DHF has four bands, attributed to a valence nπσ → π*-transition, nπσ → 3px,z/3dxz transitions, a second valence nπ → π*-transition followed by d/f Rydberg series converging to the ionization energy, respectively. All Rydberg series converging to the ionization energy have been characterized in terms of their quantum defects.

Published
2020

10. Large amplitude motions within molecules trapped in solid parahydrogen

Author

Michèle Chevalier, Claudine Crépin, Justinas Ceponkus, Alejandro Gutiérrez-Quintanilla, Rolando R. Lozada-Garcia, Jean-Michel Mestdagh, Instituto Superior de Tecnologias y Ciencias Aplicadas - InSTEC (CUBA), Institut des Sciences Moléculaires d'Orsay (ISMO), Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institute of Chemical Physics, Vilnius University [Vilnius], Dynamique Réactionnelle (DyR), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), SYSIPHE, Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Hydrogen bond, H tunnelling, Acetylacetone, [PHYS.PHYS.PHYS-ATM-PH]Physics [physics]/Physics [physics]/Atomic and Molecular Clusters [physics.atm-clus], Infrared spectroscopy, 02 engineering and technology, 010402 general chemistry, 021001 nanoscience & nanotechnology, Spin isomers of hydrogen, 01 natural sciences, Molecular physics, 0104 chemical sciences, chemistry.chemical_compound, chemistry, Molecular vibration, Intramolecular force, Molecule, nuclear spin conversion, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], parahydrogen solid, Physical and Theoretical Chemistry, 0210 nano-technology, Quantum tunnelling
Abstract

International audience; Molecules of the b-diketone and b-dialdehyde families were trapped in solid parahydrogen (pH 2) to investigate the vibrational behavior of systems containing an intramolecular hydrogen bond (IHB). In the simplest b-diketone, acetylacetone (AcAc), H transfer related to the IHB is coupled with methyl torsions. In pH 2 , the study of nuclear spin conversion (NSC) in methyl groups allows the characterisation of the influence of these large amplitude motions on the vibrational modes. The deuteration of the OH group involved in the IHB has important consequences on the vibrational spectrum of the molecule and evidence of NSC in methyl groups is difficult to obtain. In the chlorine derivative (3-chloroacetylacetone), the H-transfer is no longer coupled with methyl torsion, and NSC has undetectable effects on the IR spectrum. A search of H tunnelling splitting in the IR spectra of b-dialdehydes trapped in pH 2 was performed. A few modes of 2-chloromalonaldehyde appear as doublets and were assigned to tunnelling levels. The spectroscopic results related to large amplitude motions are detailed and discussed, highlighting puzzling effects.

Published
2018

11. Energetics and ionization dynamics of two diarylketone molecules: benzophenone and fluorenone

Author

Marc-André Gaveau, Benoît Soep, Jean-Michel Mestdagh, Majdi Hochlaf, M. Briant, Anja Röder, Zied Gouid, Lionel Poisson, Barbara K. Cunha de Miranda, Laboratoire de Modélisation et Simulation Multi Echelle (MSME), Université Paris-Est Marne-la-Vallée (UPEM)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), University Hospital of Würzburg, Dynamique Réactionnelle (DyR), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Université Paris-Est Marne-la-Vallée (UPEM), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Unimolecular ion decomposition, General Physics and Astronomy, 02 engineering and technology, 010402 general chemistry, 021001 nanoscience & nanotechnology, Photochemistry, 01 natural sciences, 0104 chemical sciences, Ion, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, [PHYS.MECA.MEMA]Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], chemistry.chemical_compound, Fluorenone, chemistry, Fragmentation (mass spectrometry), Ionization, Benzophenone, Molecule, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], Physical and Theoretical Chemistry, Ionization energy, 0210 nano-technology
Abstract

International audience; Single photon ionization and subsequent unimolecular ion decomposition were studied on jet-cooled benzophenone and fluorenone separately, using VUV synchrotron radiation in a photoion/photoelectron coincidence setup. Slow PhotoElectron Spectra (SPES) were recorded in coincidence with either the parent or the fragment ions for hν < 12.5 eV. Dissociative ionization is observed for benzophenone only. The full interpretation of the measurements, including the identification of the neutral and ionic species when dissociative ionization is at play, benefits from high level ab initio computations for determining the equilibrium structures and the energetics of the neutral and ionized molecules and of their fragments. Electronically excited states of the parent molecular ions were calculated also. From this analysis, an accurate experimental determination of the energetics of the benzophenone and fluorenone ions and of their fragmentation channels is available: adiabatic ionization energies of benzophenone at 8.923 ± 0.005 eV and of fluorenone at 8.356 ± 0.007 eV; and appearance energies of benzophenone fragment ions at 11.04 ± 0.02 eV (loss of C6H5), 11.28 ± 0.02 eV (loss of H) and 11.45 ± 0.02 eV (loss of CO). The corresponding fragmentation mechanisms are explored, showing likely concerted bonds rearrangement. Possible pre-ionizing fragmentation is discussed in light of the spectra presented. The structural rigidity of fluorenone diarylketone seems to be the origin of the inhibition of the fragmentation of its cation.

Published
2019

12. Propyne-water complexes hosted in helium droplets

Author

M. Briant, Benoît Soep, Jean-Michel Mestdagh, Marc-André Gaveau, Alejandro Gutiérrez-Quintanilla, Lionel Poisson, E. Mengesha, Institut des Sciences Moléculaires d'Orsay (ISMO), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Dynamique Réactionnelle (DyR), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), and Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010302 applied physics, Materials science, Physics and Astronomy (miscellaneous), Absorption spectroscopy, Spectrum (functional analysis), General Physics and Astronomy, chemistry.chemical_element, Ring (chemistry), Propyne, 01 natural sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, chemistry.chemical_compound, chemistry, Ab initio quantum chemistry methods, 0103 physical sciences, Moiety, Physical chemistry, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], 010306 general physics, Helium
Abstract

A HElium Nanodroplet Isolation (HENDI) experiment was performed to explore the absorption spectrum of the propyne-water complex ( C H 3 CCH ⋯ H 2 O ). Two spectral regions were investigated, near the CH stretch v1 of the propyne moiety and near the asymmetric stretch v3 of the water moiety. Ab-initio calculations were performed at the MP2/aug-cc-pVTZ level to estimate the spectroscopic constants of the free complex. This provided the necessary parameters to simulate the absorption spectrum of the complex and thus facilitate the interpretation of the experiment. The observed spectrum is consistent with a structure of the complex where two H-bonds between water and propyne form a five member ring. The later was predicted by Lopes et al. [J. Mol. Struct. 834, 258 (2007)].A HElium Nanodroplet Isolation (HENDI) experiment was performed to explore the absorption spectrum of the propyne-water complex ( C H 3 CCH ⋯ H 2 O ). Two spectral regions were investigated, near the CH stretch v1 of the propyne moiety and near the asymmetric stretch v3 of the water moiety. Ab-initio calculations were performed at the MP2/aug-cc-pVTZ level to estimate the spectroscopic constants of the free complex. This provided the necessary parameters to simulate the absorption spectrum of the complex and thus facilitate the interpretation of the experiment. The observed spectrum is consistent with a structure of the complex where two H-bonds between water and propyne form a five member ring. The later was predicted by Lopes et al. [J. Mol. Struct. 834, 258 (2007)].

Published
2019

13. Large amplitude motion within acetylene–rare gas complexes hosted in helium droplets

Author

Alexandra Viel, Jean-Michel Mestdagh, Benoît Soep, E. Mengesha, Pierre Jamet, M. Briant, Marc-André Gaveau, Jean-Michel Launay, Lionel Poisson, Dynamique Réactionnelle (DyR), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique de Rennes (IPR), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), GDR 3533 Edifices Moléculaires Isolés et Environnés, Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Université de Rennes 1 (UR1), and Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Quantum dynamics, General Physics and Astronomy, chemistry.chemical_element, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, Molecular physics, Spectral line, Physics::Plasma Physics, Bound state, Astrophysics::Solar and Stellar Astrophysics, Physical and Theoretical Chemistry, Spectroscopy, Helium, [PHYS]Physics [physics], Mesoscopic physics, Resonance, 021001 nanoscience & nanotechnology, Potential energy, 0104 chemical sciences, chemistry, Helium clusters, Astrophysics::Earth and Planetary Astrophysics, Atomic and molecular collisions, 0210 nano-technology
Abstract

International audience; Near-infrared spectroscopy of the C2H2–Ar, Kr complexes was performed in the spectral region overlapping the ν3/ν2 + ν4 + ν5 Fermi-type resonance of C2H2. The experiment was conducted along the HElium NanoDroplet Isolation (HENDI) technique in order to study the coupling dynamics between a floppy molecular system (C2H2–Ar and C2H2–Kr) and a mesoscopic quantum liquid (the droplet). Calculations were performed using a spectral element based close-coupling program and state-of-the-art 2-dimensional potential energy surfaces to determine the bound states of the C2H2–Ar and C2H2–Kr complexes and simulate the observed spectra. This furnished a quantitative basis to unravel how the superfluid and non-superfluid components of the droplet affect the rotation and the deformation dynamics of the hosted complex.

Published
2019

14. A HElium NanoDroplet Isolation (HENDI) investigation of the weak hydrogen bonding in the propyne dimer (CH 3 CCH) 2

Author

Claudine Crépin, M. Briant, Benoît Soep, Marc-André Gaveau, Alejandro Gutiérrez-Quintanilla, E. Mengesha, Jean-Michel Mestdagh, Lionel Poisson, Institut des Sciences Moléculaires d'Orsay (ISMO), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Dynamique Réactionnelle (DyR), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Photophysique Moléculaire (PPM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, 010304 chemical physics, Absorption spectroscopy, Hydrogen bond, Dimer, General Physics and Astronomy, chemistry.chemical_element, 010402 general chemistry, Propyne, 01 natural sciences, 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, chemistry.chemical_compound, Monomer, chemistry, Chemical physics, Ab initio quantum chemistry methods, 0103 physical sciences, Potential energy surface, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], Physical and Theoretical Chemistry, Helium
Abstract

International audience; A HElium Nanodroplet Isolation (HENDI) experiment was performed to explore the absorption spectra of the propyne monomer (CH3CCH), dimer and (CH3CCH)≥3 multimers in the vicinity of the CH stretch region ν1 of the monomer. Ab initio calculations were performed at the MP2 level to document the potential energy surface of the dimer. This provided the necessary parameters to simulate the absorption spectrum of the dimer and thus facilitate the interpretation of the experiment. The central result was to observe three isomers of the dimer, hence reflecting the complexity of the weak CH⋯π H-bonding when several H-donors are at play.

Published
2018

15. Multipronged mapping to the dynamics of a barium atom deposited on argon clusters

Author

Jean-Michel Mestdagh, Marc-André Gaveau, Benoît Soep, O. Gobert, M. Briant, Lionel Poisson, R. Maksimenka, and S. Awali

Subjects
Argon, 010304 chemical physics, Chemistry, General Physics and Astronomy, chemistry.chemical_element, Barium, Nanosecond, 010402 general chemistry, 01 natural sciences, 0104 chemical sciences, Excited state, 0103 physical sciences, Atom, Femtosecond, Physics::Atomic and Molecular Clusters, Cluster (physics), Physics::Atomic Physics, Physical and Theoretical Chemistry, Atomic physics, Spectroscopy
Abstract

The dynamics of an electronically excited barium atom deposited at the surface of an Ar≈500 cluster was explored in a multipronged approach which associates information from frequency-resolved nanosecond experiments and information from femtosecond time-resolved experiments. In both types of experiments, the dynamics is monitored by photoelectron and photoion spectroscopy.

Published
2016

16. Direct observation of slow intersystem crossing in an aromatic ketone, fluorenone

Author

Marc-André Gaveau, Jean-Michel Mestdagh, M. Briant, Lionel Poisson, Benoît Soep, Dynamique Réactionnelle (DyR), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
education.field_of_study, Chemistry, Population, General Physics and Astronomy, 02 engineering and technology, 010402 general chemistry, 021001 nanoscience & nanotechnology, Internal conversion (chemistry), 01 natural sciences, Molecular physics, 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, chemistry.chemical_compound, Intersystem crossing, Nuclear magnetic resonance, Fluorenone, Excited state, Benzophenone, Physical and Theoretical Chemistry, Triplet state, Ionization energy, 0210 nano-technology, education
Abstract

International audience; Direct measurements of Single vibronic Level InterSystem Crossing (SLISC) have been performed on the fluorenone molecule in the gas phase, by time resolved photoelectron and photoion spectroscopy. Vibronic transitions above the S1 nπ* origin were excited in the 432–420 nm region and the decay of S1 and growth of T13ππ* could be observed within a 10 ns time domain. The ionization potential is measured as 8.33 ± 0.04 eV. The energy of the first excited triplet state of fluorenone, T1 has been characterized directly at 18 640 ± 250 cm−1. The internal conversion of S1 to S0 is found to amount to ∼15% of the population decay, thus ISC is the dominant electronic relaxation process. ISC, although favored by the S11nπ*–T13ππ* coupling scheme, is 3 orders of magnitude less efficient than in the similar molecule benzophenone. Thus, the planarity of the fluorenone molecule disfavors the exploration of the configuration space where surface crossings would create high ISC probability, which occurs in benzophenone through surface crossings. The time evolution of S1 fluorenone is well accounted for by the statistical decay of individual levels into a quasi-continuum of T1 vibronic levels.

Published
2016

17. Self-trapping relaxation decay investigated by time-resolved photoelectron spectroscopy

Author

Benoît Soep, Aude Lietard, Jean-Michel Mestdagh, Vincent Mazet, Giovanni Piani, Marc-André Gaveau, Sylvain Faisan, Lionel Poisson, M. Briant, Dynamique Réactionnelle (DyR), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des sciences de l'ingénieur, de l'informatique et de l'imagerie (ICube), École Nationale du Génie de l'Eau et de l'Environnement de Strasbourg (ENGEES)-Université de Strasbourg (UNISTRA)-Institut National des Sciences Appliquées - Strasbourg (INSA Strasbourg), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut National de Recherche en Informatique et en Automatique (Inria)-Les Hôpitaux Universitaires de Strasbourg (HUS)-Centre National de la Recherche Scientifique (CNRS)-Matériaux et Nanosciences Grand-Est (MNGE), Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Réseau nanophotonique et optique, Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences Appliquées - Strasbourg (INSA Strasbourg), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-École Nationale du Génie de l'Eau et de l'Environnement de Strasbourg (ENGEES)-Réseau nanophotonique et optique, Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Matériaux et nanosciences d'Alsace (FMNGE), and Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Argon, Exciton, Relaxation (NMR), General Physics and Astronomy, chemistry.chemical_element, 02 engineering and technology, Trapping, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, Molecular physics, 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, X-ray photoelectron spectroscopy, chemistry, Excited state, Cluster (physics), Physical and Theoretical Chemistry, 0210 nano-technology, Excitation
Abstract

International audience; The present work combines time-resolved photoelectron spectroscopy on isolated species with high-level data processing to address an issue which usually pertains to materials science: the electronic relaxation dynamics towards the formation of a self-trapped exciton (STE). Such excitons are common excited states in ionic crystals, silica and rare gas matrices. They are associated with a strong local deformation of the matrix. Argon clusters were taken as a model. They are excited initially to a Wannier exciton at 14 eV and their evolution towards the formation of an STE has showed an unusual type of vibronic relaxation where the electronic excitation of the cluster decreases linearly as a function of time with a 0.59 ± 0.06 eV ps−1 rate. The decay was followed for 3.0 ps, and the STE formation occurred in ∼5.1 ± 0.7 ps.

Published
2018

18. Dynamics of acetylene dimers hosted in helium droplets

Author

Lionel Poisson, Marc-André Gaveau, Jean-Michel Mestdagh, M. Briant, E. Mengesha, Benoît Soep, Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Dynamique Réactionnelle (DyR), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Dimer, General Physics and Astronomy, chemistry.chemical_element, 02 engineering and technology, Deformation (meteorology), 010402 general chemistry, 01 natural sciences, [PHYS.MECA.MEMA]Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], chemistry.chemical_compound, Physics::Atomic and Molecular Clusters, Physical and Theoretical Chemistry, Physics::Chemical Physics, Quantum, Helium, Quantum tunnelling, Antisymmetric relation, 021001 nanoscience & nanotechnology, 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Acetylene, chemistry, Chemical physics, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], 0210 nano-technology, Isomerization
Abstract

International audience; The CH antisymmetric stretch of the C2H2 moieties in acetylene dimers was explored over the range 3270–3290 cm−1 using the helium nanodroplet isolation (HENDI) technique. This work is part of a general investigation which addresses the dynamical consequences of coupling the deformation motions of weakly bound complexes with a finite size quantum liquid (the helium droplet). The acetylene dimer is attractive from this point of view because one of its deformation coordinates promotes a tunneling isomerization process. A numerical simulation of the observed spectrum allows deriving a set of effective spectroscopic constants which help understanding the dynamical role played by the droplet on the rotation and deformation of the dimer.

Published
2018

19. Spectroscopy and Dynamics of K Atoms on Argon Clusters

Author

Benoit Gervais, Lionel Poisson, Jean-Michel Mestdagh, J. Douady, Slim Awali, Benoît Soep, Dynamique Réactionnelle (DyR), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Unité d’Éude des Milieux Ionisés et Réactifs [Monastir] (EMIR), Institut Préparatoire aux Etudes d'Ingénieurs de Monastir (IPEIM), Université de Monastir - University of Monastir (UM)-Université de Monastir - University of Monastir (UM), Laboratoire Francis PERRIN (LFP - URA 2453), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Caen Normandie (UNICAEN), Normandie Université (NU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), and Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Condensed Matter::Quantum Gases, Argon, Absorption spectroscopy, Photoemission spectroscopy, chemistry.chemical_element, 7. Clean energy, Photoexcitation, chemistry, Atomic orbital, Atom, Physics::Atomic and Molecular Clusters, Cluster (physics), Physics::Atomic Physics, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], Physical and Theoretical Chemistry, Atomic physics, Spectroscopy
Abstract

International audience; We present a combined experimental and simulation study of the 4s → 4p photoexcitation of the K atom trapped at the surface of ArN clusters made of a few hundred Ar atoms. Our experimental method based on photoelectron spectroscopy allows us to firmly establish that one single K atom is trapped at the surface of the cluster. The absorption spectrum is characterized by the splitting of the atomic absorption line into two broad bands, a Π band associated with p orbitals parallel to the cluster surface and a Σ band associated with the perpendicular orientation. The spectrum is consistent with observations reported for K atoms trapped on lighter inert gas clusters, but the splitting between the Π and Σ bands is significantly larger. We show that a large amount of K atoms are transiently stuck and eventually lost by the Ar cluster, in contrast with previous observations reported for alkaline earth metal systems. The excitation in the Σ band leads systematically to the ejection of the K atom from the Ar cluster. On the contrary, excitation in the Π band leads to the formation of a bound state. In this case, the analysis of the experimental photoelectron spectrum by means of nonadiabatic molecular dynamics simulation shows that the relaxation drives the system toward a basin where the coordination of the K atom is 2.2 Ar atoms on the average, in a poorly structured surface.

Published
2015

20. Ultrafast excited-state dynamics of a cyano-substituted 'proton sponge'

Author

Giovanni Piani, Wybren Jan Buma, Grzegorz Balkowski, Irena Deperasińska, Jean Michel Mestdagh, Krzysztof Oberda, Anna Szemik-Hojniak, Hong Zhang, Lionell Poisson, and Molecular Spectroscopy (HIMS, FNWI)

Subjects
Proton, 010405 organic chemistry, Chemistry, 010402 general chemistry, 01 natural sciences, 7. Clean energy, Fluorescence, Spectral line, 0104 chemical sciences, Excited state, Ultrafast laser spectroscopy, Molecule, Physical and Theoretical Chemistry, Absorption (chemistry), Atomic physics, Excitation
Abstract

The dynamics of a substituted proton sponge the 1,8-bis(dimethylamino)-4-cyanonaphthalene (DMAN-CN) molecule was investigated after excitation in the S-1 state. Experimental and theoretical information are reported. The former includes absorption, flucirescence, and time-resolved transient absorption spectra, which 'were recorded in -solution. Real-time dynamics measurements were also performed on gas-phase isolated DMAN-CN. TD DFT/6-31G(d,p) level and CIS/6-31G(d,p) excited-state calculations complement these results. This has allowed revisiting the energy transfer process between a locally excited (LE) and a charge transfer (CT) state, which is often invoked with this kind of molecule.

Published
2015

21. Approche bayésienne pour la décomposition conjointe d’une séquence de spectres de photo-électrons

Author

Jean-Michel Mestdagh, Vincent Mazet, Sylvain Faisan, Lionel Poisson, A. Masson, and Marc-André Gaveau

Subjects
Physics, Sequence, Markov random field, 020206 networking & telecommunications, 02 engineering and technology, 010402 general chemistry, Bayesian inference, 01 natural sciences, Spectral line, 0104 chemical sciences, symbols.namesake, Amplitude, Simulated annealing, 0202 electrical engineering, electronic engineering, information engineering, Calculus, symbols, Maximum a posteriori estimation, Statistical physics, Electrical and Electronic Engineering, Gibbs sampling
Abstract

This work deals with the decomposition of a temporal sequence of photoelectron spectra into a sum of peaks whose positions, amplitudes and widths are estimated. Since the peaks exhibit a (slow) evolution with time, the decomposition is performed jointly on the whole sequence to take this temporal information into account. To this end, we have developed a Bayesian model where a Markov random field favors a smooth evolution of peaks. The approach is unsupervised and a Gibbs sampler within a simulated annealing scheme enables to estimate the maximum a posteriori. We show the relevance of this approach compared with a method in which the spectra are decomposed separately and present an application on real photoelectron data.

Published
2013

22. Large amplitude motion of the acetylene molecule within acetylene-neon complexes hosted in helium droplets

Author

Jean-Michel Mestdagh, Marc-André Gaveau, M. Briant, Benoît Soep, P. de Pujo, E. Mengesha, Lionel Poisson, Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Dynamique Réactionnelle (DyR), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010304 chemical physics, General Physics and Astronomy, chemistry.chemical_element, Resonance, 010402 general chemistry, Rotation, 01 natural sciences, Spectral line, 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, chemistry.chemical_compound, Neon, Acetylene, chemistry, Physics::Plasma Physics, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Physical and Theoretical Chemistry, Atomic physics, Spectroscopy, Helium, Superfluid helium-4
Abstract

International audience; Superfluid helium droplets provide an ideal environment for spectroscopic studies with rotational resolution. Nevertheless, the molecular rotation is hindered because the embedded molecules are surrounded by a non-superfluid component. The present work explores the dynamical role of this component in the hindered rotation of C2H2 within the C2H2–Ne complex. A HENDI experiment was built and near-infrared spectroscopy of C2H2–Ne and C2H2 was performed in the spectral region overlapping the ν3/ν2 + ν4 + ν5 Fermi-type resonance of C2H2. The comparison between measured and simulated spectra helped to address the above issue.

Published
2016

23. OPT2X: Optimizing XUV optical pulses for ultrafast science in Paris-Saclay

Author

Bertrand Carré, Rodrigo Lopez-Martens, David Garzella, David Dennetières, Jean-Michel Mestdagh, Philippe Zeitoun, C. Spezzani, Maël Delhinger, Marino Marsi, François Polack, Stefan Haessler, Julien Lenfant, Lionel Poisson, Danielle Dowekon, Thierry Ruchon, Sophie Kazamias, Franck Delmotte, Laurent Nahon, and Annie Klisnick

Subjects
Engineering, Optics, business.industry, Cross disciplinary, Extreme ultraviolet, Synchrotron radiation, business, Ultrashort pulse, Characterization (materials science)
Abstract

OPT2X gathers researchers of the newly formed Paris-Saclay University with the goal of building an instrumental platform dedicated to the control, characterization and transport of ultra-short coherent XUV light pulses, in view of cross disciplinary applications in ultrafast science

Published
2016

24. Characterization of a seeded pulsed molecular beam using the velocity map imaging technique

Author

Jean-Michel Mestdagh, Marc-André Gaveau, Lionel Poisson, Aude Lietard, Korea University [Seoul], Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Dynamique Réactionnelle (DyR), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Ionizing radiation, Flow visualization, Ionization, Velocity measurement, Flow (psychology), 02 engineering and technology, 01 natural sciences, law.invention, Optics, law, 0103 physical sciences, Supersonic speed, 010304 chemical physics, business.industry, Chemistry, Mode (statistics), 021001 nanoscience & nanotechnology, Laser, Characterization (materials science), [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Atomic and molecular beam sources, Atomic physics, 0210 nano-technology, business, Molecular beam
Abstract

International audience; An experimental study has been performed to characterize the density and the velocity distribution in a pulsed molecular beam generated by a source associating a pulsed valve and an oven placed just downstream. In its operating mode, the flow is alternatively in a supersonic and effusive regime. The Velocity Map Imaging (VMI) technique associated with laser ionization allows measuring the velocity distribution and the density of molecules as a function of time during the expansion. It gives us a very precise insight into the structure of the molecule bunch, and therefore into the nature of the expansion from which the molecular beam is extracted.

Published
2016

25. Nuclear Spin Conversion to Probe the Methyl Rotation Effect on Hydrogen-Bond and Vibrational Dynamics

Author

Claudine Crépin, Wutharath Chin, Jean-Michel Mestdagh, Michèle Chevalier, Rolando R. Lozada-Garcia, Justinas Ceponkus, Laboratoire de Photophysique Moléculaire (PPM), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Francis PERRIN (LFP - URA 2453), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)

Subjects
Acetylacetone, proton tunneling, Infrared spectroscopy, 02 engineering and technology, 010402 general chemistry, Spin isomers of hydrogen, 01 natural sciences, Molecular physics, Catalysis, chemistry.chemical_compound, Computational chemistry, Molecule, Physics::Chemical Physics, 010405 organic chemistry, Hydrogen bond, Matrix isolation, matrix isolation, General Medicine, General Chemistry, 021001 nanoscience & nanotechnology, molecular dynamics, 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, chemistry, IR spectroscopy, Intramolecular force, hydrogen bonds, 0210 nano-technology, Methyl group
Abstract

International audience; A noteworthy example of a molecule with coupled large-amplitude motions is provided by acetylacetone (methyl group torsions and intramolecular hydrogen bonds). The molecule was trapped in solid parahydrogen to investigate the complex proton tunneling processes. Nuclear spin conversion in methyl groups is observed and, combined with IR spectra, documents the coupling between high frequency modes and large amplitude motions.

Published
2012

26. Photodepletion measurements of the Zr⋯F–CH3 van der Waals complex

Author

Jean-Michel Mestdagh, Marc-André Gaveau, Satchin Soorkia, and Benoît Soep

Subjects
Laser ablation, 010304 chemical physics, Chemistry, General Physics and Astronomy, 010402 general chemistry, 01 natural sciences, Mass spectrometric, 3. Good health, 0104 chemical sciences, symbols.namesake, Excited state, 0103 physical sciences, Atom, symbols, Physical and Theoretical Chemistry, Atomic physics, van der Waals force, Spectroscopy, Ground state
Abstract

We report here on the observation of the Zr⋯F–CH 3 van der Waals complexes in a laser ablation – supersonic expansion source. The complexes are studied using a combination of laser spectroscopy and time-of-flight mass spectrometric detection. We show that the (1:1) Zr⋯F–CH 3 complex is stable in the ground electronic state. By a ground state photodepletion method, we have characterized one of the transitions in the 600–700 nm region as correlating asymptotically with the z 3 F 2 0 ← a 3 F 2 atomic transition from the ground state of free Zr atom. The corresponding excited state of the Zr⋯F–CH 3 complex is reactive with activation of the C–F bond.

Published
2010

27. Photoionization of Benzophenone in the Gas Phase: Theory and Experiment

Author

M. Briant, Noura Khemiri, Jean-Michel Mestdagh, Sabri Messaoudi, Majdi Hochlaf, Benoît Soep, Lionel Poisson, Manef Abderrabba, Marc-André Gaveau, Gloria Spighi, Laboratoire de Physicochimie des Matériaux - IPEST(La Marsa, Tunisia), Institut préparatoire aux études scientifiques et techniques [La Marsa] (IPEST), Laboratoire Matériaux, Molécules et Applications (LMMA), Université de Carthage - University of Carthage-Institut préparatoire aux études scientifiques et techniques [La Marsa] (IPEST), Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire Francis PERRIN (LFP - URA 2453), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Modélisation et Simulation Multi Echelle (MSME), Université Paris-Est Marne-la-Vallée (UPEM)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), CM1405, European Cooperation in Science and Technology, Centre National de la Recherche Scientifique (CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Université Paris-Est Marne-la-Vallée (UPEM), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Photoemission spectroscopy, Ab initio, Photoelectron photoion coincidence spectroscopy, Photoionization, 7. Clean energy, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, chemistry.chemical_compound, chemistry, Excited state, Physics::Atomic and Molecular Clusters, Benzophenone, Density functional theory, Physics::Atomic Physics, Physical and Theoretical Chemistry, Atomic physics, Ionization energy, ComputingMilieux_MISCELLANEOUS
Abstract

We report on the single photoionization of jet-cooled benzophenone using a tunable source of VUV synchrotron radiation coupled with a photoion/photoelectron coincidence acquisition device. The assignment and the interpretation of the spectra are based on a characterization by ab initio and density functional theory calculations of the geometry and of the electronic states of the cation. The absence of structures in the slow photoelectron spectrum is explained by a congestion of the spectrum due to the dense vibrational progressions of the very low frequency torsional mode in the cation either in pure form or in combination bands. Also a high density of electronic states has been found in the cation. Presently, we estimate the experimental adiabatic and vertical ionization energy of benzophenone at 8.80 ± 0.01 and 8.878 ± 0.005 eV, respectively. The ionization energy as well as the energies of the excited states are compared to the calculated ones.

Published
2015

28. Gas-Phase Dynamics of Spiropyran and Spirooxazine Molecules

Author

† and Jean-Michel Mestdagh, Guy Buntinx, Kevin D. Raffael, Benoît Soep, Lionel Poisson, Laboratoire Francis PERRIN (LFP - URA 2453), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Avancé de Spectroscopie pour les Intéractions la Réactivité et l'Environnement - UMR 8516 (LASIRE), Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), and Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Centrale Lille Institut (CLIL)

Subjects
Spiropyran, Photoisomerization, Chemistry, 02 engineering and technology, General Chemistry, Electronic structure, 010402 general chemistry, 021001 nanoscience & nanotechnology, Mass spectrometry, Photochemistry, 01 natural sciences, Biochemistry, Catalysis, 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, chemistry.chemical_compound, Photochromism, Colloid and Surface Chemistry, X-ray photoelectron spectroscopy, Excited state, Organic chemistry, Molecule, 0210 nano-technology
Abstract

The gas-phase dynamics of two classes of photochromic molecules, three spiropyrans and one spirooxazine, have been investigated here using both time-resolved mass spectrometry and photoelectron spectroscopy approaches. It is, to our knowledge, the first gas-phase experiment done of these kinds of molecules. The molecules are excited at 266 nm and probed at 800 nm. The comparison of the dynamics of these four molecules has been used to propose a sequential photoisomerization mechanism involving four steps occurring in the first 100 ps. Each of these steps is discussed and related to the observed condensed-phase dynamics and to theoretical calculations.

Published
2006

29. Probing several structures of Fe(H2O)n+ and Co(H2O)n+ (n=1,…,10) cluster ions

Author

J.P. Visticot, Jean-Michel Mestdagh, F. Lepetit, L. Dukan, Lionel Poisson, P. Pradel, F. Réau, Olivier Sublemontier, Laboratoire Francis PERRIN (LFP - URA 2453), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Departement de Chimie, Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA), and Université Nice Sophia Antipolis (1965 - 2019) (UNS)

Subjects
010304 chemical physics, Collision-induced dissociation, Cluster ion, Chemistry, Binding energy, Analytical chemistry, Photofragmentation, 010402 general chemistry, Condensed Matter Physics, 01 natural sciences, 0104 chemical sciences, Ion, CID, Crystallography, Solvation shell, Fragmentation (mass spectrometry), Absorption band, 0103 physical sciences, Cluster (physics), Molecule, Physical and Theoretical Chemistry, Instrumentation, Spectroscopy
Abstract

International audience; Co(H2O)n≤10+ and Fe(H2O)n≤10+ cluster ions were generated in a source combining laser ablation and a supersonic expansion. The clusters were fragmented to get insight into their structure. Two questions were addressed: first, the arrangement of the water molecules about the metal ion, and second, the electronic properties of the solvated metal ion. Collision induced dissociation by helium was used to answer the first question, especially for the smallest clusters with n=2 and 3. This revealed the existence of filament structures where one water molecule lies in the second solvation shell about the metal ion although the first shell is not filled. The binding energies of second shell water in Co(H2O)2+ and Fe(H2O)2+ are 0.45±0.1 and 0.5±0.1 eV, respectively. The answer to the second question was provided by photofragmentation experiments where the cluster ions are illuminated at 532, 355 and 266 nm. The most striking effect is seen with cobalt ions where increasing the number n of water molecules above n=7 allows one to built up an absorption band that is known when Co+ is solvated in liquid water. The two fragmentation techniques appear as complementary.

Published
2002

30. Gas phase dynamics of triplet formation in benzophenone

Author

Benoît Soep, Marc-André Gaveau, Jean-Michel Mestdagh, Lionel Poisson, Gloria Spighi, Laboratoire Francis PERRIN (LFP - URA 2453), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Argon, Relaxation (NMR), General Physics and Astronomy, chemistry.chemical_element, Nanosecond, Internal conversion (chemistry), Photochemistry, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, chemistry.chemical_compound, chemistry, Chemical physics, Benzophenone, Physical and Theoretical Chemistry, Triplet state, Ground state, Direct process
Abstract

International audience; Benzophenone is a prototype molecule for photochemistry in the triplet state through its high triplet yield and reactivity. We have investigated its dynamics of triplet formation under the isolated gas phase conditions via femtosecond and nanosecond time resolved photoelectron spectroscopy. This represents the complete evolution from the excitation in S-2 to the final decay of T-1 to the ground state S-0. We have found that the triplet formation can be described almost as a direct process in preparing T1, the lowest reacting triplet state, from the S-1 state after S-2 -> S-1 internal conversion. The molecule was also deposited by a pick-up technique on cold argon clusters providing a soft relaxation medium without evaporation of the molecule and the mechanism was identical. This cluster technique is a model for medium influenced electronic relaxation and provides a continuous transition from the isolated gas phase to the relaxation dynamics in solution.

Published
2014

31. Competitive direct vs. indirect photochromism dynamics of constrained inverse dithienylethene molecules

Author

Benoît Soep, Aurélie Perrier, Aude Lietard, Jean-Michel Mestdagh, Lionel Poisson, Stéphane Aloïse, Denis Jacquemin, Giovanni Piani, Michinori Takeshita, Laboratoire Francis PERRIN (LFP - URA 2453), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Spectrochimie Infrarouge et Raman - UMR 8516 (LASIR), Centre National de la Recherche Scientifique (CNRS)-Université de Lille, Interfaces, Traitements, Organisation et Dynamique des Systèmes (ITODYS (UMR_7086)), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), Chimie Et Interdisciplinarité : Synthèse, Analyse, Modélisation (CEISAM), Université de Nantes - Faculté des Sciences et des Techniques, Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS), Department of Chemistry and Applied Chemistry, Interfaces, Traitements, Organisation et Dynamique des Systèmes [Avant 2020] (ITODYS (UMR_7086)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Avancé de Spectroscopie pour les Intéractions la Réactivité et l'Environnement - UMR 8516 (LASIRE), Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Centrale Lille Institut (CLIL), Université Paris Diderot - Paris 7 (UPD7)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Université de Nantes (UN)-Université de Nantes (UN)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), and Université de Lille-Centre National de la Recherche Scientifique (CNRS)

Subjects
Chemistry, Oscillation, Wave packet, Relaxation (NMR), General Physics and Astronomy, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Photochromism, Chemical physics, Computational chemistry, Excited state, Ionization, Molecule, Physical and Theoretical Chemistry, Spectroscopy
Abstract

International audience; State-of-the-art experimental and theoretical tools were used to investigate the gas-phase relaxation dynamics of various photoexcited photochromic dithienylethene molecules in situations where several relaxation channels are simultaneously at play. Unconstrained and constrained dynamics were addressed by considering unbridged and bridged molecules with a polyether bridge of various sizes (from 2 to 4 units). Time-resolved ultrafast ionization spectroscopy techniques were used to probe the dynamics. This revealed the existence of several relaxation pathways from the first excited state to the ground-state. Characteristic times were determined for each process. These channels compete at an early stage of the dynamics only when the initial wavepacket splits into two parts. A striking excited state wavepacket oscillation is observed in bridged molecules. A general reaction mechanism is proposed which rationalizes the carbon-carbon distance rule which is widely used as an empirical tool to predict the photoactivity of photochromic molecules in crystals.

Published
2014

32. Time resolved observation of the solvation dynamics of a Rydberg excited molecule deposited on an argon cluster-I: DABCO ☆ at short times

Author

Sylvain Faisan, Marc-André Gaveau, Lionel Poisson, Christophe Pothier, Vincent Mazet, Majdi Hochlaf, Slim Awali, Mounir Ben El Hadj Rhouma, Benoît Soep, Jean-Michel Mestdagh, M. Briant, Laboratoire Francis PERRIN (LFP - URA 2453), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Service des Photons, Atomes et Molécules (SPAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire de Modélisation et Simulation Multi Echelle (MSME), Université Paris-Est Marne-la-Vallée (UPEM)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des sciences de l'ingénieur, de l'informatique et de l'imagerie (ICube), École Nationale du Génie de l'Eau et de l'Environnement de Strasbourg (ENGEES)-Université de Strasbourg (UNISTRA)-Institut National des Sciences Appliquées - Strasbourg (INSA Strasbourg), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Matériaux et nanosciences d'Alsace (FMNGE), Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Réseau nanophotonique et optique, Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA), Laboratoire des Sciences de l'Image, de l'Informatique et de la Télédétection (LSIIT), Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Université Paris-Est Marne-la-Vallée (UPEM), Institut National des Sciences Appliquées - Strasbourg (INSA Strasbourg), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-École Nationale du Génie de l'Eau et de l'Environnement de Strasbourg (ENGEES)-Réseau nanophotonique et optique, Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Matériaux et nanosciences d'Alsace, Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Institut National de la Santé et de la Recherche Médicale (INSERM), Etude des Milieux Ionisés et Réactif (EMIR), Institut Préparatoire aux Etudes d'Ingénieurs de Monastir, Laboratoire des Sciences de l'Image, de l'Informatique et de la Télédétection, équipe MIV (LSIIT / MIV), Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Unité d’Éude des Milieux Ionisés et Réactifs [Monastir] (EMIR), Institut Préparatoire aux Etudes d'Ingénieurs de Monastir (IPEIM), Université de Monastir - University of Monastir (UM)-Université de Monastir - University of Monastir (UM), Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Matériaux et nanosciences d'Alsace (FMNGE), Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut National de Recherche en Informatique et en Automatique (Inria)-Les Hôpitaux Universitaires de Strasbourg (HUS)-Centre National de la Recherche Scientifique (CNRS)-Matériaux et Nanosciences Grand-Est (MNGE), Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Réseau nanophotonique et optique, and Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
education.field_of_study, 010304 chemical physics, Absorption spectroscopy, Chemistry, Population, Relaxation (NMR), Solvation, General Physics and Astronomy, 010402 general chemistry, 01 natural sciences, Molecular physics, 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, symbols.namesake, Excited state, 0103 physical sciences, Rydberg formula, symbols, Physical and Theoretical Chemistry, Atomic physics, Physics::Chemical Physics, Spectroscopy, Ground state, education, ComputingMilieux_MISCELLANEOUS
Abstract

International audience; This paper is a joint experimental and theoretical approach concerning a molecule deposited on a large argon cluster. The spectroscopy and the dynamics of the deposited molecule are measured using the photoelectron spectroscopy. The absorption spectrum of the deposited molecule shows two solvation sites populated in the ground state. The combined dynamics reveals that the population ratio of the two sites is reversed when the molecule is electronically excited. This work provides the timescale of the corresponding solvation dynamics. Theoretical calculation supports the interpretation. More generally, close examination of the short time dynamics (0-6 ps) of DABCO center dot center dot center dot Ar-n gives insights into the ultrafast relaxation dynamics of molecules deposited at interfaces and provides hence the time scale for deposited molecules to adapt to their neighborhoods.

Published
2014

33. A roaming wavepacket in the dynamics of electronically excited 2-hydroxypyridine

Author

Jean-Michel Mestdagh, Majdi Hochlaf, Martial Boggio-Pasqua, Dhananjay Nandi, Lionel Poisson, Benoît Soep, Laboratoire Francis PERRIN (LFP - URA 2453), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Modélisation et Simulation Multi Echelle (MSME), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Université Paris-Est Marne-la-Vallée (UPEM), Photochimie théorique et computationnelle (LCPQ) (PTC), Laboratoire de Chimie et Physique Quantiques (LCPQ), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées, Université Paris-Est Marne-la-Vallée (UPEM)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), and Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)

Subjects
Oscillation, Chemistry, General Physics and Astronomy, 02 engineering and technology, Conical intersection, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, Potential energy, 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Delocalized electron, Excited state, Potential energy surface, Relaxation (physics), Physical and Theoretical Chemistry, Triplet state, Atomic physics, 0210 nano-technology
Abstract

International audience; How much time does it take for a wavepacket to roam on a multidimensional potential energy surface? This combined theoretical and pump-probe femtosecond time experiment on 2-hydroxypyridine proposes an answer. Bypassing the well-established transition state and conical intersection relaxation pathways, this molecular system undergoes relaxation into the S1 excited state: the central ring is destabilized by the electronic excitation, within ∼100 fs after absorption of the pump photon, then the H-atom bound to oxygen undergoes a roaming behavior when it couples to other degrees of freedom of the molecule. The timescale of the latter process is measured to be ∼1.3 ps. Further evolution of the wavepacket is either an oscillation onto the S1 potential or a conversion into the triplet state for timescale larger than ∼110 ps. Our work introduces a new tool for the understanding of time-resolved relaxation dynamics applied to large molecules through the roaming dynamics characterized by its strongly delocalized wavepacket on flat molecular potential energy surfaces.

Published
2014

34. Spectroscopy, polarization and nonadiabatic dynamics of electronically excited Ba(Ar)n clusters: Theory and experiment

Author

J. P. Visticot, Anna I. Krylov, Marc-André Gaveau, R. B. Gerber, Jean-Michel Mestdagh, and B. Schilling

Subjects
Photoexcitation, Chemistry, Excited state, Atom, Cluster (physics), General Physics and Astronomy, Emission spectrum, Physical and Theoretical Chemistry, Atomic physics, Spectroscopy, Potential energy, Excitation
Abstract

Molecular Dynamics simulations using a surface‐hopping method for transitions between different electronic states are employed to study the dynamics following photoexcitation of the Ba(Ar)125 cluster. The results are used to interpret spectroscopic experiments on large, size‐distributed Ba(Ar)n clusters. The dynamics of the coupled electronic‐nuclear motions in the cluster involves transitions between three potential energy surfaces, corresponding to the nearly‐degenerate p‐states of the excited Ba atom. Ejection of excited Ba atoms, adsorbed on the surface of the cluster, can take place. The focus in comparing theory and experiment is on the emission spectrum from the excited clusters, on the polarization of this radiation, and on the polarization of light emitted by excited Ba atoms ejected from the cluster. Based on the good agreement found between theory and experiment, a comprehensive picture of the excited state dynamics is given. It is found that upon excitation, energy is rapidly redistributed in ...

Published
1996

35. Photochemistry of acetylacetone isolated in parahydrogen matrices upon 266 nm irradiation

Author

Justinas Ceponkus, Michèle Chevalier, Claudine Crépin, Jean-Michel Mestdagh, Rolando R. Lozada-Garcia, Wutharath Chin, Laboratoire de Photophysique Moléculaire (PPM), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Francis PERRIN (LFP - URA 2453), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)

Subjects
Hydrogen, Photochemistry, Ultraviolet Rays, Acetylacetone, General Physics and Astronomy, Infrared spectroscopy, chemistry.chemical_element, 010402 general chemistry, Spin isomers of hydrogen, 01 natural sciences, chemistry.chemical_compound, Pentanones, 0103 physical sciences, Spectroscopy, Fourier Transform Infrared, Physical and Theoretical Chemistry, Triplet state, Spectroscopy, 010304 chemical physics, 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Kinetics, chemistry, Excited state, Quantum Theory, Isomerization
Abstract

International audience; The photochemistry of the chelated enol form of acetylacetone (AcAc) was investigated by UV excitation of the S2 state at 266 nm in parahydrogen matrices, complemented by experiments in neon and normal hydrogen matrices. Infrared (IR) spectroscopy, combined with theoretical calculations, was used to identify the photoproducts. Isomerization towards various non-chelated forms (no intramolecular H-bond) of AcAc is the dominant channel whereas fragmentation is very minor. The isomerization kinetics is monitored by IR spectroscopy. Among the seven non-chelated conformers of AcAc, only three are formed in parahydrogen matrices, whereas four are observed in normal hydrogen matrices. This difference suggests that an active tunnelling process between conformers occurs in parahydrogen but is quenched in normal hydrogen where guest-host interactions are stronger. Fragmentation and isomerization of excited AcAc are discussed in the light of these new data. The role of the intermediate triplet state in the S2 → S0 relaxation is confirmed, as the importance of phonons in the condensed phase.

Published
2012

37. Theoretical investigations of the electronic states of NaXe: A comparative study

Author

Jean-Michel Mestdagh, Majdi Hochlaf, F. Ben Salem, M. Ben Bel Haj Rhouma, Fernand Spiegelman, Modélisation, Agrégats, Dynamique (LCPQ) (MAD), Laboratoire de Chimie et Physique Quantiques (LCPQ), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées, Laboratoire Francis PERRIN (LFP - URA 2453), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Modélisation et Simulation Multi Echelle (MSME), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Université Paris-Est Marne-la-Vallée (UPEM), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université Paris-Est Marne-la-Vallée (UPEM)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), and Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)

Subjects
Valence (chemistry), 010304 chemical physics, Chemistry, Ab initio, General Physics and Astronomy, 010402 general chemistry, 01 natural sciences, Electron electric dipole moment, Molecular physics, 0104 chemical sciences, Pseudopotential, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Condensed Matter::Materials Science, symbols.namesake, Dipole, Ab initio quantum chemistry methods, Excited state, 0103 physical sciences, Physics::Atomic and Molecular Clusters, Rydberg formula, symbols, Physical and Theoretical Chemistry, Atomic physics, ComputingMilieux_MISCELLANEOUS
Abstract

The electronic state properties of NaXe are investigated using ab initio methodologies and various pseudopotential approaches for comparison. The spectroscopic terms and dipole moments of the lowest electronic states up to the Na(3d) +Xe dissociation limit are determined. The difference between valence or smaller core pseudopotential on Xe is shown to be negligible and so is the difference between all-electron and valence pseudopotential completed by core-polarization treatments of Na. These calculations are used as references to test the performance of a treatment involving a zero electron pseudopotential description of xenon together with a one-electron pseudopotential description of Na. When compared with the reference calculations, the one-electron model leads to reasonable quantitative results. The potential energy curves and spectroscopic data of all Rydberg excited states of NaXe up the Na(5f)+Xe dissociation limit are determined using this method. Long distance wells and barriers in the range R = 15-40 bohrs are identified for some of the higher states with (2)Σ(+) symmetry.

Published
2012

38. Laser induced fluorescence spectroscopy of the Ca deposited on Helium and Mixed Helium/Argon Clusters

Author

Jean-Michel Mestdagh, A. Masson, M. Briant, Marc-André Gaveau, Laboratoire Francis PERRIN (LFP - URA 2453), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Argon, 010304 chemical physics, Chemistry, Photodissociation, Analytical chemistry, oscillator strengths, chemistry.chemical_element, 33.50.Dq, 31.50.Df, 33.20.Lg, 41.85.Si, 33.70.Ca, 010402 general chemistry, 01 natural sciences, Fluorescence spectroscopy, 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Xenon, monochromators, Excited state, 0103 physical sciences, Physics::Atomic and Molecular Clusters, luminescence, Emission spectrum, fluorescence, Spectroscopy, Helium, excited states
Abstract

We study the laser induced fluorescence spectroscopy of the calcium dimer deposited on helium and mixed helium∕argon clusters. In the wavelength range between 365 and 385 nm, the Ca dimer is excited from its ground state up to two excited electronic states leading to its photodissociation in Ca(1P)+Ca(1S): this process is monitored by recording the Ca(1P) fluorescence about 422.7 nm. These electronic excited states of Ca2 are respectively a diexcited one correlating to the Ca(4s 4p 3P)+Ca(4s 3d 3D) and a repulsive one correlating diabatically to the Ca(4s 4p 1P)+Ca(4s2 1S) asymptote, accounting for the dissociation of Ca2 and the observation of the subsequent Ca(1P) emission. On pure helium clusters, the fluorescence consists of the calcium atomic resonance line Ca(1S←1P) at 422.7 nm (23652 cm−1) assigned to ejected calcium, and a narrow red sided band corresponding to calcium that remains solvated on the helium cluster. Interestingly, the branching ratio to the ejection of Ca(1P) increases along with the wavelength of the excitation photon, i.e. when its energy decreases. This is contrary to what is intuitively expected and to what is really found on pure argon clusters. On mixed helium∕argon clusters, a new spectral band appears on the red side of the calcium resonance line; the intensity and the red shift of this component increase along with the argon quantity deposited on the helium cluster: it is assigned to the emission of Ca(1P) associated with the small argon aggregate embedded inside the helium cluster.

Published
2011

39. Determination of the Ground Electronic State in Transition Metal Halides: ZrF

Author

Niloufar Shafizadeh, Marc-André Gaveau, Satchin Soorkia, Jean-Michel Mestdagh, Benoît Soep, Christophe Pothier, Robert W. Field, Jacques Liévin, Laboratoire Francis PERRIN (LFP - URA 2453), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Photophysique Moléculaire (PPM), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Service de Chimie Quantique et Photophysique, Université libre de Bruxelles (ULB), Department of Chemistry, Massachusetts Institute of Technology (MIT), and Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)

Subjects
Ligand field theory, Analytical chemistry, Electrons, Electronic structure, Ligands, Vibration, 01 natural sciences, 010309 optics, Halogens, Ab initio quantum chemistry methods, 0103 physical sciences, Transition Elements, Physical and Theoretical Chemistry, 010306 general physics, Spectroscopy, Photons, Molecular Structure, Chemistry, Physical, Chemistry, Lasers, Diatomic molecule, 3. Good health, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Isotopic shift, Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization, Excited state, Quantum Theory, Thermodynamics, Ground state, Sciences exactes et naturelles
Abstract

The spectroscopy of the ZrF radical, produced by a laser ablation-molecular beam experimental setup, has been investigated for the first time using a two-color two-photon (1 + 1′) REMPI scheme and time-of-flight (TOF) mass spectrometry detection. The region of intense bands 400-470 nm has been studied, based upon the first spectroscopic observations of the isovalent ZrCl radical by Carroll and Daly.(1)The overall spectrum observed is complex. However, simultaneous and individual ion detection of the five naturally occurring isotopologues of ZrF has provided a crucial means of identifying band origins and characterization via the isotopic shift, δ iso, of the numerous vibronic transitions recorded. Hence, five (0-0) transitions, of which only two were free of overlap with other transitions, have been identified. The most intense (0-0) transition at 23113 cm -1 presented an unambiguously characteristic RQP rotational structure. From rotational contour simulations of the observed spectra, the nature of the ground electronic state is found to be unambiguously of 2Δ symmetry, leading to the assignment of this band as (0-0) 2Δ ← X 2Δ at 23113 cm -1. A set of transitions (1-0) 2Δ ← X 2Δ at 22105 cm -1 and (2-0) 2 ← X 2Δ at 22944 cm -1 involving the X 2Δ state has also been identified and analyzed. Furthermore, a second series of transitions with lesser intensity has also been related to the long-lived metastable 4Σ - state: (3-0) 4Π -1/2 ← 4Σ - at 21801 cm -1, (2-0) 4Π -1/2 ← 4Σ - at 21285 cm -1 and (2-0) 4Σ - ← 4Σ - at 23568 cm -1. These spectroscopic assignments are supported by MRCI ab initio calculations, performed using the MOLPRO quantum chemistry package, and show that the low-lying excited states of the ZrF radical are the 4Σ - and 4 states lying at 2383 and 4179 cm -1 respectively above the ground X 2Δ state. The difference in the nature of ground state and ordering of the first electronic states with TiF (X 4)(2-4)and ZrCl,(5)respectively, is examined in terms of the ligand field theory (LFT)(7)applied to diatomic molecules. These results give a precise description of the electronic structure of the low lying electronic states of the ZrF transition metal radical. © 2011 American Chemical Society., SCOPUS: ar.j, info:eu-repo/semantics/published

Published
2011

40. Reaction between Ba and N2O in large Arn clusters

Author

P. de Pujo, J. Cuvellier, J. Berlande, A. Lallement, Jean-Michel Mestdagh, J. P. Visticot, Olivier Sublemontier, C. G. Hickman, X. Biquard, and P. Meynadier

Subjects
Argon, Chemistry, Analytical chemistry, General Physics and Astronomy, chemistry.chemical_element, Quantum yield, Chemical reaction, Crossed molecular beam, Excited state, Atom, Physics::Atomic and Molecular Clusters, Cluster (physics), Physics::Chemical Physics, Physical and Theoretical Chemistry, Atomic physics, Solvent effects
Abstract

The collision between a Ba atom and an Arn cluster carrying N2O molecules has been investigated under crossed molecular beam conditions. The argon cluster acts as a solvent for the Ba+N2O reaction, which is monitored through its chemiluminescent channel forming electronically excited BaO. The effects of cluster size and the number of N2O molecules per cluster have been investigated systematically as have the effects of extra molecules present upon the cluster (CH4). It has been shown that (i) the BaO reaction product either stays solvated in the cluster or is lost from the cluster; (ii) the reaction probability between Ba and N2O is approximately unity for the clusters considered here; (iii) the chemiluminescence quantum yield decreases as the number of N2O molecules per cluster is increased. The effect of a thermal bath (the argon cluster) on the dynamics of the well studied gas phase reaction Ba+N2O is discussed.

Published
1993

41. State specific reactions of Ba(1S0) and Ba(1D2) with water and methanol

Author

Christian Alcaraz, H. Floyd Davis, Jean Michel Mestdagh, Yuan T. Lee, and Arthur G. Suits

Subjects
Alkaline earth metal, Hydrogen, Analytical chemistry, General Physics and Astronomy, chemistry.chemical_element, Chemical reaction, chemistry, Metastability, Excited state, Atom, Reactivity (chemistry), Physical and Theoretical Chemistry, Atomic physics, Ground state
Abstract

The reactions of Ba(6s2 1S0) and Ba(6s5d 1D2) with water and methanol were studied under single collision conditions using crossed molecular beams. Reaction of ground state Ba(1S)+H2O led to dominant formation of BaO+H2 at all collision energies studied (12–30 kcal/mol). Although the reaction Ba(1S)+H2O→BaOH+H could also be observed at collision energies above the endoergicity of the reaction (13 kcal/mol), it remained a minor channel even at the highest collision energy. Electronic excitation of the Ba atom reactant to the metastable 1D2 state led to a large enhancement in reactivity, but the products were BaOH+H rather than BaO+H2. The dominance of BaO+H2 from ground state Ba(1S) even at collision energies nearly equal to the Ba(1D) excitation energy of 11 395 cm−1 (∼32 kcal/mol) indicates that the observed reaction state specificity results from participation of different potential energy surfaces for reactions of ground and excited state atoms. Collisions of Ba(1S) and Ba(1D) with methanol led only to...

Published
1993

42. ChemInform Abstract: Reaction Between Ba and N2O in Large Arn Clusters

Author

Jean-Michel Mestdagh, X. Biquard, C. G. Hickman, A. Lallement, P. de Pujo, J. Cuvellier, J. P. Visticot, J. Berlande, P. Meynadier, and Olivier Sublemontier

Subjects
Argon, Chemistry, Analytical chemistry, Quantum yield, chemistry.chemical_element, General Medicine, Solvent, Crossed molecular beam, Excited state, Atom, Physics::Atomic and Molecular Clusters, Cluster (physics), Molecule, Physics::Chemical Physics
Abstract

The collision between a Ba atom and an Arn cluster carrying N2O molecules has been investigated under crossed molecular beam conditions. The argon cluster acts as a solvent for the Ba+N2O reaction, which is monitored through its chemiluminescent channel forming electronically excited BaO. The effects of cluster size and the number of N2O molecules per cluster have been investigated systematically as have the effects of extra molecules present upon the cluster (CH4). It has been shown that (i) the BaO reaction product either stays solvated in the cluster or is lost from the cluster; (ii) the reaction probability between Ba and N2O is approximately unity for the clusters considered here; (iii) the chemiluminescence quantum yield decreases as the number of N2O molecules per cluster is increased. The effect of a thermal bath (the argon cluster) on the dynamics of the well studied gas phase reaction Ba+N2O is discussed.

Published
2010

43. Unusual Quantum Interference in the S1 State of DABCO and Observation of Intramolecular Vibrational Redistribution

Author

Mama Nsangou, Jean-Michel Mestdagh, Benoît Soep, Raman Maksimenska, Lionel Poisson, Majdi Hochlaf, David H. Parker, Hochlaf, M., Laboratoire Francis PERRIN (LFP - URA 2453), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institutes of Physical and Organic Chemistry, Julius-Maximilians-Universität Würzburg [Wurtzbourg, Allemagne] (JMU), Department of Laser Physics, University of Nijmegen, Department of Chemistry and Physics, University of California, Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Modélisation et Simulation Multi Echelle (MSME), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Université Paris-Est Marne-la-Vallée (UPEM), Julius-Maximilians-Universität Würzburg (JMU), University of California (UC), Université Paris-Est Marne-la-Vallée (UPEM)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Department of Molecular and Laser Physics [Nijmegen], Institute for Molecules and Materials [Nijmegen], Radboud University [Nijmegen]-Radboud University [Nijmegen], and Radboud university [Nijmegen]-Radboud university [Nijmegen]

Subjects
Time Factors, Quantum decoherence, DABCO, 010402 general chemistry, Vibration, 01 natural sciences, Piperazines, chemistry.chemical_compound, Ab initio quantum chemistry methods, 0103 physical sciences, Physics::Atomic and Molecular Clusters, Molecule, Physics::Chemical Physics, Physical and Theoretical Chemistry, ComputingMilieux_MISCELLANEOUS, 010304 chemical physics, Chemistry, Lasers, 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, [CHIM.THEO] Chemical Sciences/Theoretical and/or physical chemistry, Intramolecular force, Molecular vibration, Femtosecond, Quantum Theory, Molecular and Laser Physics, Atomic physics, Excitation
Abstract

International audience; In this paper we report an experimental study of the time-resolved response of the molecule 1,4-diazabicyclo[2.2.2]octane (DABCO) to 266.3 nm electronic excitation of the S(1) state with a femtosecond laser. Rotational decoherence and vibrational oscillation within the S(1) state are observed. We performed state-of-the-art ab initio calculations on the ground and low electronic states of the neutral molecule and the cation, which assist in the assignment of the observed photoelectron signals. Using our theoretical and spectroscopic data, the experimental findings are interpreted in terms of an unusual quantum interference between two different vibrational modes, with only the nu = 1 level of each mode being populated.

Published
2010

44. Dynamics of highly excited barium atoms deposited on large argon clusters. I. General trends

Author

Benoît Soep, Jean-Michel Mestdagh, Lionel Poisson, Fernand Spiegelman, Marc-André Gaveau, Vincent Mazet, A. Masson, Laboratoire Francis PERRIN (LFP - URA 2453), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences de l'Image, de l'Informatique et de la Télédétection, équipe MIV (LSIIT / MIV), Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Modélisation, Agrégats, Dynamique (LCPQ) (MAD), Laboratoire de Chimie et Physique Quantiques (LCPQ), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), and Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)

Subjects
General Physics and Astronomy, chemistry.chemical_element, barium, photoionisation, 7. Clean energy, 01 natural sciences, photoelectron spectra, Ionization, 0103 physical sciences, Cluster (physics), Astrophysics::Solar and Stellar Astrophysics, Physical and Theoretical Chemistry, 010306 general physics, excited states, Argon, 010304 chemical physics, Relaxation (NMR), Barium, Photoelectric effect, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, molecular clusters, chemistry, Excited state, Femtosecond, argon, 36.40.Cg Electronic and magnetic properties of clusters - 36.40.Mr Spectroscopy and geometrical structure of clusters - 33.80.Eh Autoionization, photoionization, and photodetachment - 33.80.Rv Multiphoton ionization and excitation to highly excite, molecule-photon collisions, Atomic physics
Abstract

33.60.+q Photoelectron spectra; International audience; Ba(Ar) ≈ 750 clusters were generated by associating the supersonic expansion and the pick-up techniques. A femtosecond pump (266.3 nm)-probe (792 or 399.2 nm) experiment was performed to document the dynamics of electronically excited barium within the very multidimensional environment of the argon cluster. Barium was excited in the vicinity of the 6s9p 1P state and probed by ionization. The velocity imaging technique was used to monitor the energy distribution of photoelectrons and photoions as a function of the delay time between the pump and the probe pulses. A complex dynamics was revealed, which can be interpreted as a sequence/superposition of elementary processes, one of which is the ejection of barium out of the cluster. The latter has an efficiency, which starts increasing 5 ps after the pump pulse, the largest ejection probability being at 10 ps. The ejection process lasts at a very long time, up to 60 ps. A competing process is the partial solvation of barium in low lying electronic states. Both processes are preceded by a complex electronic relaxation, which is not fully unraveled here, the present paper being the first one in a series.

Published
2010

45. Reaction geometry from orbital alignment dependence of ion pair production in crossed‐beam Ba(1P1)–Br2reactions

Author

Hongtao Hou, H. Floyd Davis, Yuan T. Lee, Jean-Michel Mestdagh, and Arthur G. Suits

Subjects
Atomic orbital, Scattering, Plane (geometry), Chemistry, Perpendicular, General Physics and Astronomy, Geometry, Physical and Theoretical Chemistry, Atomic physics, Diatomic molecule, Beam (structure), Charged particle, Ion
Abstract

Strong orbital alignment dependence was observed for Ba+ produced in crossed‐beam reaction of Ba(1P1) with Br2. The peak of this dependence varied strongly with scattering angle for alignment of the p orbital in the scattering plane, with the maximum flux seen for perpendicular alignment with respect to the relative velocity vector. The measured Ba+ was always favored by alignment of the orbital in the scattering plane, regardless of laboratory scattering angle. The experimental results suggest that this charge‐transfer process is dominated by large impact‐parameter collisions which achieve collinear nuclear geometry and Σ orbital alignment at the crossing point. Orbital locking is probably not important owing to the large internuclear distance of the crossing region.

Published
1991

46. Dynamics of electronically inelastic collisions from 3D Doppler measurements

Author

Arthur G. Suits, P. Meynadier, J Berlande, O Sublemontier, J. P. Visticot, Thomas Gustavsson, Yuan T. Lee, de Pujo P, Jean-Michel Mestdagh, and J. Cuvellier

Subjects
Physics, chemistry.chemical_classification, chemistry, Scattering, Product (mathematics), Excited state, Momentum transfer, Inelastic collision, General Physics and Astronomy, Resonance, Atomic physics, Inelastic scattering, Inorganic compound
Abstract

Flux-velocity contour maps were obtained for the inelastic collision process Ba({sup 1}{ital P}{sub 1})+O{sub 2}N{sub 2}{r arrow}Ba({sup 3}{ital P}{sub 2})+O{sub 2}N{sub 2} from Doppler scans of scattered Ba({sup 3}{ital P}{sub 2}) taken over a range of probe laser directions in a crossed-beam experiment. Collision with O{sub 2} resulted in sharply forward scattered Ba({sup 3}{ital P}{sub 2}), with efficient conversion of inital electronic energy into O{sub 2} internal energy and little momentum transfer. Collision with N{sub 2} was dominated by wide-angle scattering with most of the available electronic energy appearing in product translation. The results suggest the importance of large-impact-parameter collisions and a near-resonant energy transfer in the case of O{sub 2}, while for N{sub 2} close collisions dominate despite the presence of an analogous near-resonant channel. The results represent the first direct experimental demonstration of a near-resonant quenching process.

Published
1991

47. Ultrafast dynamics of acetylacetone (2,4-pentanedione) in the S2 state

Author

Benoît Soep, Stéphane Coussan, Pascale Roubin, Jean-Michel Mestdagh, Lionel Poisson, Laboratoire Francis PERRIN (LFP - URA 2453), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Physique des interactions ioniques et moléculaires (PIIM), and Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Time Factors, VIBRATIONAL DYNAMICS, MALONALDEHYDE, Acetylacetone, ELECTRON-DIFFRACTION, 010402 general chemistry, 01 natural sciences, Biochemistry, PHOTODISSOCIATION DYNAMICS, Catalysis, chemistry.chemical_compound, Colloid and Surface Chemistry, PHOTOISOMERIZATION, Ionization, Pentanones, 0103 physical sciences, Vibrational energy relaxation, INTRAMOLECULAR PROTON-TRANSFER, 010304 chemical physics, Molecular Structure, RESOLVED PHOTOELECTRON-SPECTROSCOPY, Resonance, Hydrogen Bonding, General Chemistry, NITROGEN MATRIX, Potential energy, UV, 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, chemistry, Excited state, Intramolecular force, IR, Quantum Theory, Atomic physics, Excitation
Abstract

International audience; The dynamics of the enolic form of acetylacetone (E-AcAc) was investigated using a femtosecond pump-probe experiment. The pump at 266 nm excited E-AcAc in the first bright state, S-2(pi pi*). The resulting dynamics was probed by multiphoton ionization at 800 rim. It was investigated for 80 ps on the S-2(pi pi*) and S-1(n pi*) potential energy surfaces. An important step is the transfer from S-2 to S-1 that occurs with a time constant of 1.4 +/- 0.2 ps. Before, the system had left the excitation region in 70 +/- 10 fs. An intermediate step was identified when E-AcAc traveled on the S-2 surface. Likely, it corresponds to an accidental resonance in the detection scheme that is met along this path. More importantly, some clues are given that an intramolecular vibrational energy relaxation is observed, which transfers excess vibrational energy from the enolic group O-H to the other modes of the molecule. The present multistep evolution of excited E-AcAc probably also describes, at least qualitatively, the dynamics of other electronically excited beta-diketones.

Published
2008

48. Transition-state spectroscopy of the photoinduced Ca + CH3F reaction. 3. Reaction following the local excitation to Ca(4s3d 1D)

Author

Marc-André Gaveau, C. Sanz Sanz, Benoît Soep, Jean-Michel Mestdagh, Eric Gloaguen, M. Collier, and Octavio Roncero

Subjects
Pseudopotential, Reaction mechanism, Absorption spectroscopy, Atomic electron transition, Chemistry, Absorption band, Excited state, Physical and Theoretical Chemistry, Atomic physics, Potential energy, Excitation
Abstract

13 pages, 11 figures, 2 tables.-- Printed version published Feb 21, 2008., The Ca* + CH3F → CaF* + CH3 reaction was studied both experimentally and theoretically. The reaction was photoinduced in Ca···CH3F complexes, which were illuminated by a tunable laser in the range 18000−24000 cm-1. The absorption band that leads to the reaction extends between 19000 and 23000 cm-1. It is formed of three broad overlapping structures corresponding to the excitation of different electronic states of the complex. The two structures of lowest energy were considered in detail. They are associated with two series of respectively 2 and 3 molecular states correlating to Ca(4s3d 1D) + CH3F at infinite separation between Ca and CH3F. The assignment of these structures to specific electronic transitions of the complex stemmed from theoretical calculations where the Ca···CH3F complex is described by a linear Ca−F−C backbone. 2D potential energy surfaces were calculated by associating a pseudopotential description of the [Ca2+] and [F7+] cores, a core polarization operator on calcium, an extensive Gaussian basis, and a treatment of the electronic problem at the CI-MRCI level. All the excited levels correlating to the 4s2 1S, 4s3d 1D, and 4s4p 1P levels of Ca in the Ca + CH3F channel were documented in a calculation that explored the rearrangement channels where either Ca + CH3F or CaF + CH3 are formed. Then, wavepacket calculations on the 2D-PES's allowed one to simulate the absorption spectrum of the complex, in an approximation where the various electronic states of the complex are not coupled together. The assignment above stemmed from this. The second outcome of the calculation was that whatever the excited level of the complex that is considered, the reaction has to proceed through energy barriers. The electronic excitation of the complex on the red side of the absorption band does not seem to deposit enough energy in the system to overcome these barriers (even the lowest one) or to stimulate tunneling reactions. An alternative reaction mechanism involving a transfer to triplet PES's is proposed., Partial support is acknowledged from the Spanish-French bilateral grant Picasso-no 09252TM and from the European Community through the PICNIC network (Product Imaging and Correlation: Non-adiabatic Interactions in Chemistry) under contract number HPRN-CT-2002-00183.

Published
2008

49. Direct Observation of Microscopic Solvation at the Surface of Clusters by Ultrafast Photoelectron Imaging

Author

Lionel Poisson, Eric Gloaguen, Jean-Michel Mestdagh, Benoît Soep, Alejandro Gonzalez, Majed Chergui, Laboratoire Francis PERRIN (LFP - URA 2453), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de spectroscopie ultrarapide, and Ecole Polytechnique Fédérale de Lausanne (EPFL)

Subjects
Argon, 010304 chemical physics, Photoemission spectroscopy, Chemistry, Matrix isolation, Solvation, chemistry.chemical_element, 010402 general chemistry, 01 natural sciences, 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, symbols.namesake, Excited state, Photoelectron spectra, Rydberg state, UV and visible spectra (microscopic solvation at surface of argon clusters by ultrafast photoelectron imaging), 0103 physical sciences, Cluster (physics), Rydberg formula, symbols, Physics::Atomic and Molecular Clusters, microscopy solvation surface argon cluster ultrafast photoelectron imaging, Physical and Theoretical Chemistry, Atomic physics, Physics::Chemical Physics
Abstract

International audience; We report on microscopic observation of solvation by argon atoms of excited states of an ethylenic-like molecule, TDMAE (tetrakis dimethylaminoethylene). Two experimental methods were used: gas phase dynamics for the observation of the evolution through excited states, matrix isolation spectroscopy for characterization of the initial states. Excited state dynamics was recorded after the molecule had been deposited on the surface of a large argon cluster (n ≈ 100) by pick-up. The deposited cluster was characterized by mass spectrometry and by its shifted photoelectron spectrum. The time evolution of the system was visualized by femtosecond pump/probe velocity map imaging of photoelectrons. The time evolution of deposited TDMAE excited at 266 nm can be modeled via a modified three state model, as in the free molecule. The initially excited state is of valence character, and a Rydberg state mediates the passage to a zwitterionic configuration. The specific solvation of Rydberg states by the surface of the cluster was directly observed and is discussed. It represents the striking outcome of the present work. It is inferred that differently from the gas phase, solvated Rydberg states resulting from state mixing within a Rn/λ complex in the presence of the argon surface are reached. Solvation of these Rydberg states should be effective through interaction of the ion core of the excited molecules with the cluster.

Published
2008

50. Low Field Laser Ionization of Argon Clusters: The Remarkable Fragmentation Dynamics of Doubly Ionized Clusters

Author

Lionel Poisson, Marc-André Gaveau, Richard Taïeb, Jean-Michel Mestdagh, Benoît Soep, Jérémie Caillat, Alfred Maquet, Kevin D. Raffael, Dynamique Réactionnelle (DyR), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Laboratoire Interactions, Dynamiques et Lasers (ex SPAM) (LIDyl), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Francis PERRIN (LFP - URA 2453), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Chimie Physique - Matière et Rayonnement (LCPMR), Institut de Chimie du CNRS (INC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), ANR-05-BLAN-0295,ATTO-SCIENCE,Génération et caractérisation d'impulsions attosecondes pour l'étude de dynamiques atomiques et moléculaires ultrarapides(2005), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), and Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Fission, General Physics and Astronomy, chemistry.chemical_element, 7. Clean energy, 01 natural sciences, Ion, Autoionization, Ionization, 0103 physical sciences, Physics::Atomic and Molecular Clusters, 010306 general physics, Nuclear Experiment, Physics, [PHYS.PHYS.PHYS-OPTICS]Physics [physics]/Physics [physics]/Optics [physics.optics], Argon, 010304 chemical physics, [PHYS.PHYS.PHYS-ATOM-PH]Physics [physics]/Physics [physics]/Atomic Physics [physics.atom-ph], Coulomb explosion, PACS: 36.40.Qv, 32.80.Dz, 82.50.Pt, 82.53.k, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, chemistry, Excited state, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], Atomic physics, Valence electron, PACS: 36.40.Qv, 32.80.Dz, 82.50.Pt, 82.53.-k
Abstract

International audience; We have investigated the fission following a Coulomb explosion in argon clusters (up to $Ar_{800}$) irradiated by a femtosecond infrared laser with moderate intensity $I_{L}$≈$10^{13}$ W $cm^{−2}$. We report the a priori surprising observation of well-defined velocity distributions of the ionized fragments $Ar^{+}_{n

Published
2007

Catalog

Books, media, physical & digital resources
See catalog results