Séverine Boyé-Péronne

Université Paris-Sud 11, Paris, Ile-de-France, France

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Publications (19)38.45 Total impact

  • Séverine Boyé-Péronne, Dolores Gauyacq, Jacques Liévin
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    ABSTRACT: The first quantitative description of the Rydberg and valence singlet electronic states of vinylidene lying in the 0-10 eV region is performed by using large scale ab initio calculations. A deep analysis of Rydberg-valence interactions has been achieved thanks to the comprehensive information contained in the accurate Multi-Reference Configuration Interaction wavefunctions and an original population analysis highlighting the respective role played by orbital and state mixing in such interactions. The present theoretical approach is thus adequate for dealing with larger than diatomic Rydberg systems. The nine lowest singlet valence states have been optimized. Among them, some are involved in strong Rydberg-valence interactions in the region of the Rydberg state equilibrium geometry. The Rydberg states of vinylidene present a great similarity with the acetylene isomer, concerning their quantum defects and Rydberg molecular orbital character. As in acetylene, strong s-d mixing is revealed in the n = 3 s-d supercomplex. Nevertheless, unlike in acetylene, the close-energy of the two vinylidene ionic cores (2)A1 and (2)B1 results into two overlapped Rydberg series. These Rydberg series exhibit local perturbations when an accidental degeneracy occurs between them and results in avoided crossings. In addition, some Δl = 1 (s-p and p-d) mixings arise for some Rydberg states and are rationalized in term of electrostatic interaction from the electric dipole moment of the ionic core. The strongest dipole moment of the (2)B1 cationic state also stabilizes the lowest members of the n = 3 Rydberg series converging to this excited state, as compared to the adjacent series converging toward the (2)A1 ionic ground state. The overall energies of vinylidene Rydberg states lie above their acetylene counterpart. Finally, predictions for optical transitions in singlet vinylidene are suggested for further experimental spectroscopic characterization of vinylidene.
    The Journal of chemical physics. 11/2014; 141(17):174317.
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    ABSTRACT: (3 + 1) resonantly enhanced multiphoton ionization (REMPI) spectroscopy coupled to photoelectron spectroscopy (REMPI-PES) has been carried out to study the Rydberg states of HC3N in the 77,000–90,000 cm region. Ab initio calculations (energies and optimized equilibrium geometries) have been performed for the first time for the low-lying Π, ÃΣ and Π states of the cation HC3N in order to help the analysis. Thanks to the combination of the three-photon REMPI spectra, one-photon spectrum and photoelectron spectra, unambiguous assignments of the Rydberg series and their vibrationally excited members are proposed. The electronic Rydberg structure of cyanoacetylene is very similar to that of C2H2 and HCN (almost identical quantum defects), fully supporting the present analysis. New three-photon allowed Rydberg series are identified belonging to ns and nd series. The three-photon vibrational band assignments, confirmed by the photoelectrons spectra, reveal excitation of only one or two quanta of the ν2 (C ≡ N) mode. Apparent discrepancies between the three-photon REMPI spectrum and the one-photon absorption spectrum are removed via a minor re-assignment of the absorption spectrum previously analysed by Connors et al. J. Chem. Phys. 60(12), 5011 (1974). Finally the observed analogy with C2H2 and HCN can be rationalized by a partial relocalization of the 2π electrons upon excitation to Rydberg states converging to the Π state of HC3N as predicted by the present ab initio calculations on the cation core.
    Molecular Physics 01/2012; · 1.67 Impact Factor
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    ABSTRACT: UV laser excitation of cryogenic solids doped with cyanoethyne, HC(3)N, led to an in situ creation of longer carbon-nitrogen chains, namely HC(5)N, C(4)N(2), and C(6)N(2), heralded by their strong visible luminescence. HC(5)N and C(4)N(2) molecules can form, most probably, within HC(3)N aggregates linked by hydrogen bonds, while the reaction occurring between two isolated, photochemically created C(3)N radicals yields C(6)N(2). This latter species, dicyanobutadiyne, is easily detected in Ar, Kr, N(2), as well as in parahydrogen solids. The C(6)N(2) phosphorescence is identified here for the first time. The reported carbon chain coupling reactions in rigid environments are of interest for astrochemistry of interstellar ices.
    Physical Chemistry Chemical Physics 08/2011; 13(37):16780-5. · 4.20 Impact Factor
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    ABSTRACT: The absolute photoionization cross section of C2H5 has been measured at 10.54 eV using vacuum ultraviolet (VUV) laser photoionization. The C2H5 radical was produced in situ using the rapid C2H6 + F → C2H5 + HF reaction. Its absolute photoionization cross section has been determined in two different ways: first using the C2H5 + NO2 → C2H5O + NO reaction in a fast flow reactor, and the known absolute photoionization cross section of NO. In a second experiment, it has been measured relative to the known absolute photoionization cross section of CH3 as a reference by using the CH4 + F → CH3 + HF and C2H6 + F → C2H5 + HF reactions successively. Both methods gave similar results, the second one being more precise and yielding the value: σC2H5ion = (5.6 ± 1.4) Mb at 10.54 eV. This value is used to calibrate on an absolute scale the photoionization curve of C2H5 produced in a pyrolytic source from the C2H5NO2 precursor, and ionized by the VUV beam of the DESIRS beamline at SOLEIL synchrotron facility. In this latter experiment, a recently developed ion imaging technique is used to discriminate the direct photoionization process from dissociative ionization contributions to the C2H5+ signal. The imaging technique applied on the photoelectron signal also allows a slow photoelectron spectrum with a 40 meV resolution to be extracted, indicating that photoionization around the adiabatic ionization threshold involves a complex vibrational overlap between the neutral and cationic ground states, as was previously observed in the literature. Comparison with earlier photoionization studies, in particular with the photoionization yield recorded by Ruscic et al.(1) is also discussed.
    The Journal of Physical Chemistry A 05/2011; 115(21). · 2.77 Impact Factor
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    ABSTRACT: Methane photolysis has been performed at the two Vacuum UltraViolet (VUV) wavelengths, 121.6 nm and 118.2 nm, via a spectrally pure laser pump-probe technique. The first photon is used to dissociate methane (either at 121.6 nm or at 118.2 nm) and the second one is used to ionise the CH(2) and CH(3) fragments. The radical products, CH(3)(X), CH(2)(X), CH(2)(a) and C((1)D), have been selectively probed by mass spectrometry. In order to quantify the fragment quantum yields from the mass spectra, the photoionisation cross sections have been carefully evaluated for the CH(2) and CH(3) radicals, in two steps: first, theoretical ab initio approaches have been used in order to determine the pure electronic photoionisation cross sections of CH(2)(X) and CH(2)(a), and have been rescaled with respect to the measured absolute photoionisation cross section of the CH(3)(X) radical. In a second step, in order to take into account the substantial vibrational energy deposited in the CH(3)(X) and CH(2)(a) radicals, the variation of their cross sections near threshold has been simulated by introducing the pertinent Franck-Condon overlaps between neutral and cation species. By adding the interpolated values of CH quantum yields measured by Rebbert and Ausloos [J. Photochem., 1972, 1, 171-176], a complete set of fragment quantum yields has been derived for the methane photodissociation at 121.6 nm, with carefully evaluated 1σ uncertainties: Φ[CH(3)(X)] = 0.42 ± 0.05, Φ[CH(2)(a)] = 0.48 ± 0.05, Φ[CH(2)(X)] = 0.03 ± 0.08, Φ[CH(X)] = 0.07 ± 0.01. These new data have been measured independently of the H atom fragment quantum yield, subject to many controversies in the literature. From our results, we evaluate Φ(H) = 0.55 ± 0.17 at 121.6 nm. The quantum yields for the photolysis at 118.2 nm differ notably from those measured at 121.6 nm, with a substantial production of the CH(2)(X) fragment: Φ[CH(3)(X)] = 0.26 ± 0.04, Φ[CH(2)(a)] = 0.17 ± 0.05, Φ[CH(2)(X)] = 0.48 ± 0.06, Φ[CH(X)] = 0.09 ± 0.01, Φ(H) = 1.31 ± 0.13. These new data should bring reliable and essential inputs for the photochemical models of the Titan atmosphere.
    Physical Chemistry Chemical Physics 02/2011; 13(18):8140-52. · 4.20 Impact Factor
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    ABSTRACT: Threshold photoelectron spectra (TPES) of the isotopomers of the methyl radical (CH3, CH2D, CHD2, and CD3) have been recorded in the 9.5−10.5 eV VUV photon energy range using third generation synchrotron radiation to investigate the vibrational spectroscopy of the corresponding cations at a 7−11 meV resolution. A threshold photoelectron−photoion coincidence (TPEPICO) spectrometer based on velocity map imaging and Wiley−McLaren time-of-flight has been used to simultaneously record the TPES of several radical species produced in a Ar-seeded beam by dc flash-pyrolysis of nitromethane (CHxDyNO2, x + y = 3). Vibrational bands belonging to the symmetric stretching and out-of-plane bending modes have been observed and P, Q, and R branches have been identified in the analysis of the rotational profiles. Vibrational configuration interaction (VCI), in conjunction with near-equilibrium potential energy surfaces calculated by the explicitly correlated coupled cluster method CCSD(T*)-F12a, is used to calculate vibrational frequencies for the four radical isotopomers and the corresponding cations. Agreement with data from high-resolution IR spectroscopy is very good and a large number of predictions is made. In particular, the calculated wavenumbers for the out-of-plane bending vibrations, ν2(CH3+) = 1404 cm−1, ν4(CH2D+) = 1308 cm−1, ν4(CHD2+) = 1205 cm−1, and ν2(CD3+) = 1090 cm−1, should be accurate to ca. 2 cm−1. Additionally, computed Franck−Condon factors are used to estimate the importance of autoionization relative to direct ionization. The chosen models globally account for the observed transitions, but in contrast to PES spectroscopy, evidence for rotational and vibrational autoionization is found. It is shown that state-selected methyl cations can be produced by TPEPICO spectroscopy for ion−molecule reaction studies, which are very important for the understanding of the planetary ionosphere chemistry.
    The Journal of Physical Chemistry A 03/2010; 114(14). · 2.77 Impact Factor
  • B. Gans, S. Boyé-Péronne, S. Douin, D. Gauyacq
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    ABSTRACT: Photolysis of methane in Titan's stratosphere is the starting point of gas phase carbon chemistry. Quantitative studies of methane photolytic products are of utmost importance for Titan atmosphere models. With this aim, two experimental strategies are presented in this article. Preliminary results demonstrate the possibility of using CRDS absorption coupled with pulsed photolysis on the example of a halogenated derivative of methane: Trichloromethane (CHCl_3).
    EAS Publications Series 01/2010;
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    ABSTRACT: A pyrolysis source coupled to a supersonic expansion has been used to produce the CH3 radical from two precursors, iodomethane CH3I and nitromethane CH3NO2. The relative ionization yield of CH3 has been recorded at the SOLEIL Synchrotron Radiation source in the range 9.0−11.6 eV, and its ionization threshold has been modeled by taking into account the vibrational and rotational temperature of the radical in the molecular beam. The relative photoionization yield has been normalized to an absolute cross section scale at a fixed wavelength (118.2 nm, σiCH3 = 6.7−1.8+2.4 Mb, 95% confidence interval) in an independent laboratory experiment using the same pyrolysis source, a vacuum ultraviolet (VUV) laser, and a carefully calibrated detection chain. The resulting absolute cross section curve is in good agreement with the recently published measurements by Taatjes et al.,(1) although with an improved signal-to-noise ratio. The absolute photoionization cross section of CH3I at 118.2 nm has also been measured to be σiCH3I = (48.2 ± 7.9) Mb, in good agreement with previous electron impact measurements. Finally, the photoionization yield of the iodine atom in its ground state 2P3/2 has been recorded using the synchrotron source and calibrated for the first time on an absolute cross section scale from our fixed 118.2 nm laser measurement, σiI2P3/2 = 74−23+33 Mb (95% confidence interval). The ionization curve of atomic iodine is in good agreement, although with slight variations, with the earlier relative ionization yield measured by Berkowitz et al.(2) and is also compared to an earlier calculation of the iodine cross section by Robicheaux and Greene.(3) It is demonstrated that, in the range of pyrolysis temperature used in this work, all the ionization cross sections are temperature-independent. Systematic care has been taken to include all uncertainty sources contributing to the final confidence intervals for the reported results.
    The Journal of Physical Chemistry A 11/2009; 114(9). · 2.77 Impact Factor
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    Fabrice Laruelle, Séverine Boyé-Péronne, Dolores Gauyacq, Jacques Liévin
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    ABSTRACT: A quantitative characterization of the Rydberg and valence singlet electronic states of acetylene lying in the 5-10.7 eV region is performed by using large-scale ab initio calculations. A special attention is paid on the comparison between the present calculations and Mulliken's concepts for Rydberg states, based on single-electron and single-configuration description. Most of the properties of the Rydberg states have been qualitatively understood via this comparison, mainly shown by the shape and size of the outer Rydberg molecular orbital. More quantitatively, Rydberg-valence mixing has been evaluated in several excited energy regions, as for instance, the interaction between the ' (1pig)2 1Ag doubly excited valence state and the manifold of electronic components of the np series, or the interaction between the 1pig 1Bu valence state and the 3dpig 1Sigma(u)+ Rydberg state. The rapid predissociation of the lowest 3s(sigma) 1Piu Rydberg state has been interpreted as a case of Rydbergization, earlier predicted by Mulliken.
    The Journal of Physical Chemistry A 08/2009; 113(47):13210-20. · 2.77 Impact Factor
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    ABSTRACT: Due to their stability, diamond materials are expected to be present in different environments of the interstellar medium. Indeed, nanometer size diamond cristals have been extracted from carbonaceous chondrites and two emission features (observed at 3.43 mum and 3.53 mum) in the spectra of HD 97048 and Elias1 have been assigned to these species. Despite high astrophysical relevance, very few is known about the structural properties and dynamics of the molecular building blocks of larger species : the diamondoid molecules. These molecules consist of sp3 hybridized carbon cages where dangling bonds are terminated by hydrogen atoms. The infrared spectra of neutral molecules conforted the assignment of the 3.43 mum and 3.53 mum emission features to nanometer size diamondoid systems. In order to improve the understanding of the possible process leading to the IR emission features, we recorded the IR spectra of the deshydrogenated cationic species of adamantane, diamantane and triamantane (using Infrared Multi Photon Dissociation technique with the free electron laser FELIX) as well as the VUV spectra of adamantane and diamantane (obtained thanks to the Threshold Photo Electron Photo Ion Coincidence technique at the DESIRS beamline of the synchrotron SOLEIL). We will show the results of these spectra and the preliminary analysis. Saslaw and Gaustad, Nature, 221, 160 (1969) Lewis et al., Nature, 326, 160 (1987) van Kerckhoven et al., Astronomy and Astrophysic, 384, 568 (2002) Pirali et al., The Astrophysical Journal, 661, 919 (2007)
    06/2009;
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    ABSTRACT: Hydrocarbon radicals CxHy are constituents of various planetary atmospheres, in particular Titan, as a result of the methane photochemistry induced by the solar radiation. They contribute to the neutral chemistry, but are also important for the ionosphere through their photoionisation leading to their cations CxHy +. These cations are also produced by ion-molecule reactions starting from the reaction of the primary ions CH4 + and CH3 + which are created in the non-dissociative and dissociative photoionisation of CH4. This work aims at caracterizing the VUV photoionisation of small hydrocarbon radicals as a function of photon energy. The objective is to provide laboratory data for modelers on the spectroscopy, the thermochemistry, and the reactivity of the radicals and their cations. The hydrocarbon radicals are much less caracterized than stable molecules since they have to be produced in situ in the laboratory experiment. We have adapted at Orsay [1-3] a pyrolysis source (Figure 1) well suited to produce cold beams of hydrocarbon radicals to our experimental setups. Available now at Orsay, we have two new sources of VUV radiation, complementary in terms of tunability and resolution, that can be used for these studies. The first one is the DESIRS beamline [4] at the new french synchrotron, SOLEIL. The second one is the VUV laser developped at the Centre Laser de l'Université Paris-Sud (CLUPS) [5]. At SOLEIL, a photoelectron-photoion coincidence spectrometer is used to monitor the photoionisation on a large photon energy range. At the CLUPS, a pulsedfield ionisation (PFI-ZEKE) spectrometer allows studies at higher resolution on selected photon energies. The first results obtained with these new setups will be presented. References [1] Fischer, I., Schussler, T., Deyerl, H.J., Elhanine, M. & Alcaraz, C., Photoionization and dissociative photoionization of the allyl radical, C3H5. Int. J. Mass Spectrom., 261 (2-3), 227-233 (2007) [2] Schüßler, T., Roth, W., Gerber, T., Alcaraz, C. & Fischer, I., The vacuum ultraviolet photochemistry of radicals: C3H3 and C2H5. Phys. Chem. Chem. Phys., 7 (5), 819-825 (2005) [3] Schüßler, T., Deyerl, H. J., Dummler, S., Fischer, I., Alcaraz, C. & Elhanine, M., The vacuum ultraviolet photochemistry of the allyl radical investigated using synchrotron radiation J. Chem. Phys., 118 (20), 9077-80 (2003) [4] DESIRS, http://www.synchrotronsoleil. fr/portal/page/portal/Recherche/LignesLumiere/ DESIRS [5] CLUPS, http://www.clups.u-psud.fr/
    09/2008;
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    ABSTRACT: The 193 nm laser irradiation of cyanoacetylene (HCCCN) that was isolated in rare gas solids led to a long-lived luminescence (origin at 3.58 eV), which was assigned to the a (3)Sigma(+)-X (1)Sigma(+) system of cyanoacetylide (CCCN(-)). The identification, which involved (15)N and (2)H isotopic substitution studies, is based on vibronic spacings in the phosphorescence spectrum (compared to previous infrared absorption measurements and to theoretical results regarding CCCN(-) vibrational frequencies), as well as on a BD(T)/cc-pVTZ prediction for the singlet-triplet energy gap in this anion (3.61 eV). The same emission was also generated from KrHC(3)N mixtures subjected to a glow electric discharge immediately before the solidification (cold-window-radial-discharge technique).
    The Journal of Chemical Physics 05/2008; 128(16):164304. · 3.12 Impact Factor
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    ABSTRACT: The CH radical production induced by 193nm two-photon photolysis of CHCl3 has been measured for the first time via the cavity ring-down absorption spectroscopy of its A–X bands, using a commercial nanosecond pulsed dye laser. The range of pressure and laser intensity, as well as the time window detection, have been carefully chosen to ensure a constant CH number density during the measurement and to avoid post-photolysis reactivity. Internal energy distribution of the CH(X2II) fragment has been derived from population distribution simulations, leading to an average vibrational temperature Tvib=1900±50K and rotational temperature Trot=300±20K. Two competing mechanisms can be invoked for the CH production channel: either two-photon absorption via resonant excited states of CHCl3 leading to dissociation of excited CHCl3, or two-photon sequential dissociation via the formation of the vibrationally excited CHCl2 fragment. The latter mechanism is proposed to be the prominent process for CH formation.
    Chemical Physics 01/2008; 351(1):77-82. · 1.96 Impact Factor
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    ABSTRACT: Visible emission bands coming from UV-irradiated cyanoacetylene isolated in frozen inert gas solids (Ar, Kr, N2) were discovered and tentatively assigned to the C3N radical.
    12/2007;
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    K. Alnama, S. Boyé-Péronne, A.-L. Roche, D. Gauyacq
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    ABSTRACT: (3 + 1) and (3 + 2) Resonantly Enhanced Multiphoton (REMPI) spectroscopy has been carried out to study the Rydberg states of C2H4 in the region 55000–83000 cm−1. Differences and similarities were observed between these three-photon spectra and the one-photon absorption spectrum. First, the disappearance of the strong π−π* V ← N valence transition from the REMPI spectra allowed disentanglement of the vibrational structure of the 3s Rydberg transition from the V ← N quasi-continuum, and a search for additional weak transitions. Earlier vibrational assignments from the absorption spectrum have been confirmed in the REMPI analysis of the 3s ← N and ns, nd ← N transition systems, although with very different band intensities. This analysis has provided additional weak band assignments involving the ν3 mode in the observed Rydberg transitions. New electronic components (3dπ y , 4dπ y , 5dπ y ) of the nd complex, which are three-photon allowed but one-photon forbidden, have been tentatively assigned. The photoelectron (PES) spectra of the 3s and 3dσ lowest vibrational levels have revealed a deviation from a pure Rydberg character, in apparent contradiction with previous (2 + 1) REMPI-PES data involving gerade vibronic levels of the 3s Rydberg state, which led to a prominent Rydberg character for this state. Rydberg–valence and Rydberg–Rydberg vibronic interactions mediated via non-symmetric modes could explain the different behaviour between gerade and ungerade vibronic levels of the ethylene Rydberg states.
    Molecular Physics 06/2007; 105(Nos. 11-12):1743-1756. · 1.67 Impact Factor
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    ABSTRACT: The photolysis of allene and propyne, two isomers of C3H4, has been investigated in the excitation energy range of 7–30 eV using vacuum ultraviolet synchrotron radiation. The visible fluorescence excitation spectra of the excited neutral photofragments of both isomers were recorded within the same experimental conditions. Below the first ionization potential (IP), this fluorescence was too weak to be dispersed and possibly originated from C2H or CH2 radicals. Above IP, three excited photofragments have been characterized by their dispersed emission spectra: the CH radical (A 2Δ-X 2Π), the C2 radical (d 3Πg–a 3Πu, “Swan’s bands”), and the H atom (4–2 and 3–2 Balmer lines). A detailed analysis of the integrated emission intensities allowed us to determine several apparition thresholds for these fragments, all of them being interpreted as rapid and barrierless dissociation processes on the excited potential energy surfaces. In the low energy range explored in this work, both isomers exhibit different intensity distributions in their fragment emission as a function of the photolysis energy, indicating that mutual allene↔propyne isomerization is not fully completed before dissociation occurs. The effect of isomerization on the dissociation into excited fragments is present in the whole excitation energy range albeit less important in the 7–16 eV region; it gradually increases with increasing excitation energy. Above 19 eV, the fragment distribution is very similar for the two isomers.
    The Journal of Chemical Physics 01/2007; 126(4):044304-044304-11. · 3.12 Impact Factor
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    ABSTRACT: The A-X bands of the CH radical, produced in a 248 nm two-photon photolysis or in a supersonic jet discharge of CHBr(3), have been observed via cavity ring-down absorption spectroscopy. Bromoform is a well-known photolytic source of CH radicals, though no quantitative measurement of the CH production efficiency has yet been reported. The aim of the present work is to quantify the CH production from both photolysis and discharge of CHBr(3). In the case of photolysis, the range of pressure and laser fluences was carefully chosen to avoid postphotolysis reactions with the highly reactive CH radical. The CH production efficiency at 248 nm has been measured to be Phi=N(CH)N(CHBr(3))=(5.0+/-2.5)10(-4) for a photolysis laser fluence of 44 mJ cm(-2) per pulse corresponding to a two-photon process only. In addition, the internal energy distribution of CH(X (2)Pi) has been obtained, and thermalized population distributions have been simulated, leading to an average vibrational temperature T(vib)=1800+/-50 K and a rotational temperature T(rot)=300+/-20 K. An alternative technique for producing the CH radical has been tested using discharge-induced dissociation of CHBr(3) in a supersonic expansion. The CH product was analyzed using the same cavity ring-down spectroscopy setup. The production of CH by discharge appears to be as efficient as the photolysis technique and leads to rotationally relaxed radicals.
    The Journal of Chemical Physics 10/2006; 125(11):114312. · 3.12 Impact Factor
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    Séverine Boyé-Péronne, Dolores Gauyacq, Jacques Liévin
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    ABSTRACT: The planar isomerization routes of the vinylidene/acetylene cation in the lowest electronic states are accurately examined for the first time, by using large scale MRCI and CCSDT calculations in a complementary way. They are compared with the similar calculations performed for the neutral ground state isomerization. An accurate value of the adiabatic ionization potential of vinylidene (11.26 eV) is predicted. The vinylidene cation lowest state, 1 2A1, follows an almost flat pathway with a shallow secondary minimum on the 1 2A' potential energy surface, before suddenly dropping to the stable acetylene cation ground state, X 2Piu. It is therefore confirmed to be completely unstable with respect to isomerization. The first excited state of the vinylidene cation, 1 2B1, which also correlates with the 2Piu ground state of acetylene cation along a 2A' isomerization route, has been studied at the same level of calculation. This 1 2B1 state is lying only 0.15 eV above the 1 2A1 state, and exhibits a potential energy barrier of 0.55 eV which explains the earlier assignment of this symmetry to the ground state of vinylidene cation. In addition to large scale calculations, a comprehensive description of the important steps of isomerization drawn from a very simple model involving monoconfigurational states is presented. In particular, the behavior of one unique orbital, namely, the 5a1 outer molecular orbital, is shown to completely govern the molecular geometry and energy evolution along the isomerization route of the ground state cation C2H2+.
    The Journal of Chemical Physics 07/2006; 124(21):214305. · 3.12 Impact Factor
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    ABSTRACT: As methane is the main precursor of Titan’s chemistry, its photolytic behaviour is of great importance for the understanding of Titan’s atmospheric system. Thus, the main purpose of this paper is to present a critical review about available laboratory methane photolysis results. The way these results are further exploited in photochemical models of Titan’s atmosphere is also discussed, as those models may lead to different and sometimes contradictory conclusions. Following this literature discussions, pertinent aspects of a new experimental project for a re-examination of methane photochemistry in the frame of new Titan’s atmospheric simulations are also described.
    Advances in Space Research 01/2005; · 1.18 Impact Factor