Publications of Françoise Motte-Tollet
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See detailElectronic excitation and optical cross sections of methylamine and ethylamine in the UV-VUV spectral region
Hubin-Franskin, Marie-Jeanne ULiege; Delwiche, Jacques ULiege; Giuliani, A. et al

in Journal of Chemical Physics (2002), 116(21), 9261-9268

The high resolution ultraviolet (UV)-vacuum ultraviolet (VUV) photon absorption spectra of methylamine and ethylamine was discussed using synchrotron radiation. It was found that in methylamine, the ... [more ▼]

The high resolution ultraviolet (UV)-vacuum ultraviolet (VUV) photon absorption spectra of methylamine and ethylamine was discussed using synchrotron radiation. It was found that in methylamine, the energies of the absorption bands were centered at 5.7, 7.2 and 8.7 eV. The optical oscillator strengths of both molecules for the 5-14 eV energy range were also reported. [less ▲]

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See detailElectronic excitation and oscillator strength of ethyl bromide by vacuum ultraviolet photoabsorption and electron energy loss spectroscopy
Giuliani, Alexandre; Tollet, Françoise ULiege; Delwiche, Jacques ULiege et al

in Journal of Chemical Physics (2000), 112(14), 6285-6292

The high resolution vacuum ultraviolet photoabsorption spectrum of ethyl bromide has been recorded between 5 and 10.15 eV (248-122 nm) using synchrotron radiation. It exhibits a broad structureless ... [more ▼]

The high resolution vacuum ultraviolet photoabsorption spectrum of ethyl bromide has been recorded between 5 and 10.15 eV (248-122 nm) using synchrotron radiation. It exhibits a broad structureless valence band centred at 6.1 eV of low cross section followed by a region dominated by excitation of Rydberg states. A high resolution photoelectron spectrum (PES) of the lowest energy ionization band has been obtained and provides ionization energies necessary for identification of related Rydberg-excited states. Also, analysis of the vibrational fine structure in the PES has allowed identification of the normal vibrational modes excited and their wave numbers in the ion. These data, in turn, have been used in the assignment of the lowest energy photoabsorption bands arising from electron excitation into the 5s Rydberg orbital. The electron energy loss spectrum, recorded from 6.5 to 14.1 eV, under electric-dipole conditions, confirms the magnitude of the photoabsorption cross-section values obtained using the synchrotron radiation and extends the differential and optical oscillator strength values up to 14.004 eV. © 2000 American Institute of Physics. [less ▲]

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See detailElectronic excitation and oscillator strength of ethyl iodide by VUV photoabsorption and electron energy loss spectroscopy
Giuliani, Alexandre; Tollet, Françoise ULiege; Delwiche, Jacques ULiege et al

in Journal of Chemical Physics (1999), 110(21), 10307-10315

A high resolution VUV photoabsorption spectrum of ethyl iodide has been recorded between 4 and 10.2 eV (310-120 nm) using synchrotron radiation. The spectrum consists of a broad structureless absorption ... [more ▼]

A high resolution VUV photoabsorption spectrum of ethyl iodide has been recorded between 4 and 10.2 eV (310-120 nm) using synchrotron radiation. The spectrum consists of a broad structureless absorption band centered at 4.78 eV, followed by a region dominated by excitation of Rydberg states. A high resolution photoelectron spectrum (PES) of the lowest energy ionization band has been obtained and provides ionization energies necessary for identification of related Rydberg-excited states. Also, analysis of the vibrational fine structure in the PES has allowed identification of the normal vibrational modes excited and their wave numbers in the ion. These, in turn, have been used in the assignment of the lowest energy photoabsorption bands arising from electron excitation into the 6s Rydberg orbital. An electron energy loss spectrum has also been recorded from 5.8 to 14.2 eV, under electric-dipole conditions. It confirms the magnitude of the photoabsorption cross section values obtained using the synchrotron radiation and extends the differential and optical oscillator strength values up to 14.2 eV. © 1999 American Institute of Physics. [less ▲]

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See detailElectron spectroscopy of resonance-enhanced vibrational excitations of gaseous and solid tetrahydrofuran
Lepage, M.; Letarte, S.; Michaud, M. et al

in Journal of Chemical Physics (1998), 109(14), 5980-5986

We report intramolecular vibrational excitation of tetrahydrofuran (THF) in both the gas and solid phase induced by 1-30 eV electrons. High-resolution electron-energy-loss spectra reveal selective ... [more ▼]

We report intramolecular vibrational excitation of tetrahydrofuran (THF) in both the gas and solid phase induced by 1-30 eV electrons. High-resolution electron-energy-loss spectra reveal selective vibrational enhancement of THF for different impact energies, indicating the presence of at least three resonances (i.e., temporary anion states), located near 4, 7.5, and 10 eV, as well as many possibly overlapping higher-lying resonances. We also report electron-energy-loss spectra for different THF film thicknesses. Besides fundamental vibrational excitation, we observe several energy loss peaks due to overtones and combination vibrational modes. The present vibrational losses are assigned in compliance with published optical measurements. The similarities between the solid THF and gaseous cyclopentane spectra suggest that the resonances in both molecules could have a common origin and hence need not be attributed to the presence of the oxygen nonbonding electrons in THF. © 1998 American Institute of Physics. [less ▲]

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See detailOn the high-resolution HeI photoelectron spectrum of Cl2O
Tollet, Françoise ULiege; Delwiche, Jacques ULiege; Heinesch, Jacques ULiege et al

in Chemical Physics Letters (1998), 284(5-6), 452-458

The high-resolution HeI (58.4 nm) photoelectron spectrum of dichlorine monoxide, Cl2O, has been recorded in the region of the four lowest-energy ionic electronic states. Formation of the ion in its ground ... [more ▼]

The high-resolution HeI (58.4 nm) photoelectron spectrum of dichlorine monoxide, Cl2O, has been recorded in the region of the four lowest-energy ionic electronic states. Formation of the ion in its ground and excited electronic states is accompanied in each case by vibrational excitation. In particular, the vibrational structure of the first and second excited states of Cl2O+ is resolved. Analysis of the vibrational progressions associated with formation of the various ionic states has been completed, allowing confirmation of the symmetry and bonding characteristics of the four highest-energy occupied molecular orbitals of Cl2O. [less ▲]

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See detailPhotoabsorption and near-threshold electron energy-loss spectroscopy of OClO
Marston, G.; Walker, I. C.; Mason, N. J. et al

in Journal of Physics: B Atomic Molecular and Optical Physics (1998), 31(15), 3387-3405

The spectroscopy of chlorine dioxide, OClO, has been investigated using the techniques of dissociative electron attachment (DEA), near-threshold electron energy loss (EEL, 0-10 eV) and optical absorption ... [more ▼]

The spectroscopy of chlorine dioxide, OClO, has been investigated using the techniques of dissociative electron attachment (DEA), near-threshold electron energy loss (EEL, 0-10 eV) and optical absorption (2.5-10.8 eV). Mass and energy analyses of the ions formed in the DEA processes show that at energies above about 3 eV, the product ions are predominantly near-thermal Cl-, suggesting that the accompanying oxygen atoms are excited electronically. All features observed in the EEL experiments are in regions of optical absorption, indicating that the optically dark doublet and quartet states have energies which overlap optically allowed transitions. The optical spectrum itself is in good qualitative agreement with previous measurements, but there are differences in relative absorption cross sections. Alternative interpretations of some spectral features are proposed. [less ▲]

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See detailAbsolute cross sections for the VUV optical absorption of Cl2O in the 6.5-9.7 eV energy range
Tollet, Françoise ULiege; Ska, M.-P.; Marston, G. M. et al

in Chemical Physics Letters (1997), 275(3-4), 298-306

The VUV photoabsorption spectrum of dichlorine monoxide has been recorded between 6.5 and 9.7 eV photon energies using the UK Daresbury Synchrotron Radiation facility. The spectrum consists of a broad ... [more ▼]

The VUV photoabsorption spectrum of dichlorine monoxide has been recorded between 6.5 and 9.7 eV photon energies using the UK Daresbury Synchrotron Radiation facility. The spectrum consists of a broad structureless band centred at 7.25 eV followed by several vibrationally resolved high-intensity bands. The 7.25 eV band has been interpreted in terms of the excitation of a dissociative valence excited state while the higher-energy electronic bands (above 7.5 eV) have been classified into several (n = 3, 4) Rydberg states linked with the ionic ground state and its lowest-energy excited states. An analysis of the vibrational progressions associated with the excitation of the various Rydberg states has been completed. © 1997 Elsevier Science B.V. [less ▲]

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See detailResonant vibrational excitation of furan by low energy electron impact
Tollet, Françoise ULiege; Eustatiu, G.; Roy, D.

in Journal of Chemical Physics (1996), 105(17), 7448-7453

Our purpose was to investigate the resonant vibrational excitation of furan (C4H4O) in its electronic ground state by electron collisions. The electron energy loss measurements have been carried out at ... [more ▼]

Our purpose was to investigate the resonant vibrational excitation of furan (C4H4O) in its electronic ground state by electron collisions. The electron energy loss measurements have been carried out at intermediate and low impact energies for a scattering angle of 30°. The spectra show peaks or groups of peaks corresponding to the excitation of the fundamental normal modes as also of the first harmonics and combinations. The energy dependence curve for the excitation of the C-H stretching vibrational modes is also reported for the impact energy range of 3-10 eV. It exhibits a broad structureless band with a maximum centered around 6 eV, which reveals an excitation mechanism through the intermediate of a shape resonance built on the electronic ground state of the neutral molecule. A comparison with benzene is made in order to help the analysis and to assign the nature as well as the symmetry of the resonance. © 1996 American Institute of Physics. [less ▲]

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See detailVibrational excitation of methane by 15 and 30 eV intermediate-energy electron impact
Tollet, Françoise ULiege; Heinesch, J.; Gingell, J. M. et al

in Journal of Chemical Physics (1996), 106(14), 5990-6000

Absolute measurements of differential electron-collision cross sections have been performed for the vibrational excitation of methane in its electronic ground state at impact energies of 15 eV and, for ... [more ▼]

Absolute measurements of differential electron-collision cross sections have been performed for the vibrational excitation of methane in its electronic ground state at impact energies of 15 eV and, for the first time, at 30 eV, in the 8°-95° angular range. The normalization to the absolute scale has been carried out using the inelastic/elastic ratios and the absolute elastic differential cross section obtained from a relative flow technique recently developed in our laboratory, in which the elastic differential cross section of methane was compared to that of nitrogen at each impact energy and at each scattering angle. Special attention has been given to the small scattering angular range (≤40°) where minima have been observed in the vibrational cross sections and where simultaneous independent measurements have been made on two different electron spectrometers. © 1997 American Institute of Physics. [less ▲]

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See detailInner-shell excitation of monocyanoethylene, trans-dicyanoethylene and allylcyanide by electron energy loss spectroscopy
Hubin-Franskin, Marie-Jeanne ULiege; Aouni, H.; Duflot, D. et al

in Journal of Chemical Physics (1996), 106(1), 35-45

Inner-shell excitation spectra of gaseous monocyanoethylene, trans-dicyanoethylene, and allylcyanide have been measured at C1 s and N1 s edges using 2 keV electron collisions in quasi-dipolar excitation ... [more ▼]

Inner-shell excitation spectra of gaseous monocyanoethylene, trans-dicyanoethylene, and allylcyanide have been measured at C1 s and N1 s edges using 2 keV electron collisions in quasi-dipolar excitation conditions and the electron energy loss spectroscopy. The energy resolution has allowed the observation of transitions from different carbon sites. Ab initia calculations have been made to help the assignment of the experimental features. The spectra below the core-electron ionization limit have been interpreted in terms of transitions to the lowest-energy valence unoccupied molecular orbitals shown to be of π* type in each molecule. The effects of the conjugation between the multiple bonds on the spectra and on the splitting of the π* type molecular orbitals have been discussed. Strong electronic relaxation effects have been evidenced. © 1997 American Institute of Physics. [less ▲]

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See detailElectronic and vibrational excitation of acrylonitrile by low and intermediate energy electrons
Tollet, Françoise ULiege; Messina, D.; Hubin-Franskin, Marie-Jeanne ULiege

in Journal of Chemical Physics (1995), 103(1), 80-89

Electronic and vibrational excitation of acrylonitrile induced by 3-50 eV energy electrons has been investigated by the electron energy loss spectroscopy. Electronic excitation spectra have been recorded ... [more ▼]

Electronic and vibrational excitation of acrylonitrile induced by 3-50 eV energy electrons has been investigated by the electron energy loss spectroscopy. Electronic excitation spectra have been recorded for 30 and 50 eV impact energies at a 10° scattering angle in the energy loss range from 5.5 to 11.5 eV, corresponding to the excitation of electrons belonging to the outermost-valence-shell molecular orbitals. We have reviewed the assignment of the valence excited states occurring in the 5.5-9 eV energy loss region. The vibrational patterns associated with the two lowest-energy singlet valence excited states have also been re-examined. Moreover, we have proceeded for the first time to the analysis and attribution of several Rydberg series converging to the ionic ground state and to its two lowest-energy electronic excited states. The study of the excitation function of the C-H stretching modes of acrylonitrile in the 3-11 eV electron impact energy range has shown evidence of a broad shape resonance built on the electronic ground state of the molecule and centered at 5.85 eV. This resonance contributes to a preferential excitation of the C-H stretching modes suggesting that the charge distribution of the additional electron is very likely that of a σ* (C-H) valence molecular orbital. A comparison has been made between the resonances observed in C2H4 and CH2CHCN, in order to discuss the symmetry of the resonant state and also to analyze the substitution effect of the cyanogen group. © 1995 American Institute of Physics. [less ▲]

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See detailVibrational excitation of methylamine by electron impact in the 4.5-30 eV energy range
Tollet, Françoise ULiege; Hubin-Franskin, Marie-Jeanne ULiege; Collin, Jacques ULiege

in Journal of Chemical Physics (1992), 97(10), 7314-7322

Vibrational excitation of gaseous methylamine induced by 4.5-30 eV energy electrons has been investigated by the electron energy loss spectroscopy. The ratios of the differential cross sections for ... [more ▼]

Vibrational excitation of gaseous methylamine induced by 4.5-30 eV energy electrons has been investigated by the electron energy loss spectroscopy. The ratios of the differential cross sections for excitation of the vibrational modes and for elastic scattering measured as a function of the electron kinetic energies show that at 15 and 30 eV, the vibrational excitation occurs mainly through a direct mechanism. The absolute vibrationally elastic and inelastic differential cross sections have been measured at these impact energies. The cross sections for the inelastic scattering are strongly dependent on the vibrational mode which is excited. © 1992 American Institute of Physics. [less ▲]

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See detailResonant vibrational excitation of methylamine by low energy electron impact
Tollet, Françoise ULiege; Hubin-Franskin, Marie-Jeanne ULiege; Collin, Jacques ULiege

in Journal of Chemical Physics (1990), 93(11), 7843-7850

The study of the excitation functions of the NH2 and CH 3 stretching modes of methylamine in the 4-12 eV electron impact energy range shows evidence of a broad shape resonance built on the electronic ... [more ▼]

The study of the excitation functions of the NH2 and CH 3 stretching modes of methylamine in the 4-12 eV electron impact energy range shows evidence of a broad shape resonance built on the electronic ground state and centered at 7.5 eV. This resonance is formed by the trapping of the incident electron in the second unoccupied molecular orbital and is of A " symmetry. The elastic and inelastic angular differential cross sections measured in the 10°-90° range suggest a dominant p character. A second shape resonance located at higher energy contributes mainly to the enhancement of the CH3 deformation modes and is very likely of A ' symmetry. A comparison is made between the resonances observed in NH3 and CH 3 NH2. The effect of the methyl substitution is briefly discussed. © 1990 American Institute of Physics. [less ▲]

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