Y. Ellinger's research while affiliated with French National Centre for Scientific Research and other places

Publications (159)

Article
A consensus has progressively developed that the path towards complex organic molecules (COMs) could be favored by the icy mantles of interstellar dust particles. However the question of whether activation energy is required to promote those reactions is open. This work deals with the simplest process thought to increase complexity i.e. successive...
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The analysis of the organic matter of meteorites made it possible to identify over 70 amino acids (AA), including 8 of those found in living organisms. However, their relative abundances vary drastically with the type of the carbonaceous chondrite, even for isomers of same chemical formula. In this report we address the question whether this differ...
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Context. In spite of the permanent damage suffered from the radiation field (cosmic rays, X-rays, and intense UV-visible radiations), interstellar grains are still covered by ices mantles whose role in interstellar chemistry is well beyond any doubt. This clearly means that the destruction of the ice cover has to be counterbalanced by efficient rec...
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Context. Most of the compounds detected in the interstellar medium (ISM) that possess isomers correspond to the thermodynamically most stable isomer of a given chemical formula. Using the minimun energy principle (MEP) as a pragmatic tool is particularly efficient for less than six atoms, but for larger systems combinatorial analysis gives an intra...
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Context. Although H 2 O is the most important molecular material found in the solid state in the interstellar medium, the chemical routes leading to ice through surface reactions are still a matter of discussion. Three reaction pathways proposed in the past are at the heart of current research: hydrogenation of atomic oxygen, molecular oxygen, and...
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Context. All but one complex organic molecule (COM) detected so far in the interstellar medium (ISM) are achiral; propylene oxide (c-C 2 H 3 O)-CH 3 is the only exception to this. Finding other chiral species is a priority for astrobiology to progress in the understanding of the emergence of life. Whatever the conditions of their formation, i.e., g...
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Context. Beyond NH 3 , only one primary alkylamine, CH 3 NH 2 , has been identified in the interstellar medium and the reason why is still not understood: its formation could occur in the gas phase or in icy environments. Aims. To consider any possible difference between the formation of primary and secondary amines, we studied the hydrogenation pr...
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The origin of cometary volatiles remains a major open question in planetary science. Comets may have either agglomerated from crystalline ices condensed in the protosolar nebula (PSN) or from amorphous ice originating from the molecular cloud and interstellar medium. Here, based on the recent argon, krypton, and xenon measurements performed by the...
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Context: The analysis of isomeric species of a compound observed in the interstellar medium (ISM) is a useful tool to understand the chemistry of complex organic molecules. It could, likewise, assist in the detection of new species. Aims: Our goal consists in analyzing one of the two most stable species of the C3H4O family, methyl ketene, whose...
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The deficiencies of argon, krypton, and xenon observed in the atmosphere of Titan as well as anticipated in some comets might be related to a scenario of sequestration by H3+ in the gas phase at the early evolution of the solar nebula. The chemical process implied is a radiative association, evaluated as rather efficient in the case of H3+, especia...
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Context. Helium, the second most abundant element in the Universe, with a relative abundance of He/H ~ 1/10, has never been observed in any other form than that of a neutral atom (He) or an ion (He ⁺ ) in the interstellar medium. Since He is a noble gas its non-observation as part of neutral molecular systems is understandable, but it is very surpr...
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S2 has been observed for decades in comets, including comet 67P/Churyumov-Gerasimenko. Despite the fact that this molecule appears ubiquitous in these bodies, the nature of its source remains unknown. In this study, we assume that S2 is formed by irradiation (photolysis and/or radiolysis) of S-bearing molecules embedded in the icy grain precursors...
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Molecular oxygen has been detected in the coma of comet 67P/Churyumov-Gerasimenko with abundances in the 1--10\% range by the ROSINA-DFMS instrument on board the Rosetta spacecraft. Here we find that the radiolysis of icy grains in low-density environments such as the presolar cloud may induce the production of large amounts of molecular oxygen. We...
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The heavy noble gas deficiencies observed in Titans atmosphere and in comets have been proposed to be related to a sequestration process by H3+ in the gas phase at the early protosolar nebula. Chemical thermodynamics and astrophysics modeling are favorable to this hypothesis, as presented in preceding papers. However, there is a point still to be r...
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The detection of ArH+ has revived the interest in the search for noble gas containing species. Despite helium being the second most abundant element in the universe (He/H ∼ 1/10), it has never been observed in any other form than that of a neutral/ionized atom in the interstellar medium. Because He is the “most noble” gas, its non-observation as pa...
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Context. The results of an observational search for gas phase urea, (NH 2) 2 CO toward the Sgr B2-LMH region, have been reported recently. In spite of strong presumptions, whether it is urea or another species (for example an isomer) seems to remain a pending question. Aims. In this note, we consider the energetic aspect of this would-be detection...
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Conditions in the protosolar nebula have left their mark in the composition of cometary volatiles, thought to be some of the most pristine material in the solar system. Cometary compositions represent the end point of processing that began in the parent molecular cloud core and continued through the collapse of that core to form the protosun and th...
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Context. The CHON generic chemical formula covers different isomers such as isocyanic acid (HNCO), cyanic acid (HOCN), fulminic acid (HCNO), and isofulminic acid (HONC); the first three have been identified in a large variety of environments in the interstellar medium (ISM). Several phenomena could be at the origin of the observed abundances, such...
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Observations of comet C/1995O1 Hale-Bopp during the spring of 1997 led to the discovery of a neutral sodium tail whose origin is still not clearly understood. Here, we propose an interpretation for the origin ofthis sodium tail, which is based upon chemical grounds. Starting from Na + trapped chemically during the condensation of refractory materi...
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The recent publication that some bacteria could use arsenic instead of phosphorus for building their DNA triggered a large controversy in the astro/exobiology community. Most comments claim that such a substitution is not possible. Here, we address the same question of the presence of As in DNA from a pure theoretical point of view, beyond any biol...
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Life on Earth, as we know it to day, is inseparable from homochirality. The presence of an enantiomeric excess in carbonaceous chondrites is well documented; among the different hypotheses considered to explain this undisputed fact, we chose to investigate the possibilities open by a selective adsorption on a chiral surface that would engage a proc...
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We address the problem of the sequestration of Ar, Kr, and Xe by H_3^+ in the gas-phase conditions encountered during the cooling of protoplanetary disks when H_3^+ is competing with other species present in the same environment. Using high-level ab initio simulations, we try to quantify other sequestration possibilities involving He, H_5^+, H2O, a...
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Context. Glycine, the simplest of amino acids, has been found in several carbonaceous meteorites collected on Earth, though its presence in the interstellar medium (ISM) has never been confirmed as of today. It is now considered that its synthesis took place in the icy mantles of interstellar grains, but it remains unclear how glycine, once synthes...
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A recent controversy about the presence of arsenic in biological systems prompted us to investigate the possible replacement of phosphorus by arsenic in prebiotic species small enough to be potentially identified in space. Systematic computational experiments were carried out on simple systems able to form a peptide or analogous bond. Density Funct...
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Context. Glycine, the simplest of aminoacids, has been found in several carbonaceous meteorites. It remains unclear, however, wether glycine is formed in the interstellar medium (ISM) and therefore available everywhere in the Universe. For this reason, radioastronomers have searched for many years unsuccessfully to detect glycine in the ISM. Aims:...
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We present a combined theoretical and experimental study of the adsorption of two pairs of organic isomers, (i) acetic acid AA (CH3COOH) and methyl formate MF (HCOOCH3), and (ii) ethanol EtOH (CH3CH2OH) and dimethyl ether DME (CH3OCH3), onto crystalline water ice surfaces at low temperatures. Both approaches show that, for each pair, the most stabl...
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Complex organic molecules have been observed in the interstellar medium in comets and meteorites. Among these compounds are the building blocks that may have led to prebiotic systems and ultimately to the origin of life. In the panspermia hypothesis, the survival and the transfer of the amino acids from space to planets is a necessary condition for...
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We report a theoretical study of the physisorption of molecular hydrogen, H2, on a major component of the interstellar dust, namely, the polyaromatic carbonaceous grains. Going beyond the model of the polycyclic aromatic hydrocarbon freeflyers and its theoretical treatment within the super molecule approach, we consider the graphene surface in a De...
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As part of the Molecules and Interstellar Ices project, we report the first theoretical results obtained on one of the possible mechanisms for the reconstruction of the ice mantle of interstellar grains after irradiation by the radiation field. In the ISM, the growth of the ice mantle is assumed to proceed more by radical recombination O + H + H th...
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In this report we address the question of whether some chiral molecules have a probability of being detected in the interstellar medium (ISM). It is a crucial question since life on Earth, as we know it today, is inseparable from homochirality. Under these conditions, the identification of any chiral species in the interstellar medium (ISM) would b...
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The question of the relative stability of the complex organic molecules (COM) under the interstellar radiation field is a crucial question, especially in the context of the panspermia hypothesis for which their survival during the transfer from space to the Earth is a necessary condition for the appearance of life (Ehrenfreund et al 2001, 2002). As...
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Context. The hunt for the interstellar complex organic molecules (COMs) supposed to be the building blocks of the molecules at the origin of life is a challenging but very expensive task. It starts with laboratory experiments, associated with theoretical calculations, that give the line frequencies and strengths of the relevant molecules to be iden...
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Un nouveau développement de la méthode PCILO est présenté dans le cadre des approximations INDO. Le nombre de configurations prises en compte est considérablement augmenté par rapport à la version CNDO originale. L'énergie de corrélation des doublets libres est incluse dans le traitement. Les barrières d'inversion calculées sont correctes et les gé...
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Finding complex organic molecules in the interstellar medium (ISM) is a major concern for understanding the possible role of interstellar organic chemistry in the synthesis of prebiotic species. The present interdisciplinary report is a prospective study aimed at helping detection of heteroaromatic compounds or at least of some of their isomers in...
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In this report we address the question of whether some chiral molecules have a probability of being detected in the interstellar medium (ISM). To this end we rely on the Minimum Energy Principle which states that the most abundant isomer of a given generic formula should be that of lowest energy. The relative stability of the chiral molecules with...
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The successive hydrogenation of CO has been investigated by two methods. The first is hydrogenation of a CO surface. The second is co-injection of CO molecules and H atoms. Both methods have been performed at 3 and 10 K. In the first method, the interaction of H atoms with solid CO at 10 K shows that CO is consumed to form H(2)CO and CH(3)OH. No tr...
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Recent studies on the formation of XH(3)(+) noble gas complexes have shown strategic implications for the composition of the atmospheres of the giant planets as well as for the composition of comets. One crucial factor in the astrophysical process is the relative abundances of the noble gases versus H(3)(+). It is the context in which the possibili...
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The hunt for complex organic molecules (COMs) is a major concern for understanding the possible role of interstellar chemistry in the synthesis of the molecules that ultimately may be at the origin of life. A comprehensive screening of the 14 species effectively observed under 32 different isomeric forms in the interstellar medium has been done by...
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We study the efficiency of the noble gas sequestration by the ion H+3 in the form of X H+3 complexes (with X = argon , krypton, or xenon) in gas-phase conditions similar to those encountered during the cooling of protoplanetary disks. We show that X H+3 complexes form very stable structures in the gas phase and that their binding energies are much...
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The origin of Titan and its atmosphere dominated by nitrogen and methane is still uncertain. A puzzling feature of the satellite's atmosphere is the non-detection of the primordial noble gases krypton and xenon by the Huygens probe, present in the atmosphere of Jupiter and presumably Saturn. The carbon monoxide to methane ratio is ∼ 10-3 in Titan's...
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The present report is a prospective study aimed at finding phosphorus containing compounds for astrobiology. Since PN, PC and HCP are the only species detected so far, it was deemed reasonable to enlarge the quest for phosphorus compounds to mixed carbon oxygen containing compounds [C,xH,O,P] analogue to the CHON family. Ab initio Møller-Plesset (M...
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Amino acids are currently identified in carbonaceous chondrites but none are yet observed for sure in the interstellar medium. The question of the relative stability of these prebiotic compounds with respect to the other possible species of same chemical formula is addressed by means of quantum chemical simulations. It is shown that glycine, alanin...
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Since the PAH hypothesis has been proposed for interpreting the UIR bands, the question of the intensity of the 3.3 mum has been largely debated. An in-depth study of the CH fragment using density functional theory (DFT) is presented that shows the striking difference of the dipole moment functions mu = f (rCH) between the neutral CH and the ionize...
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The affinity of H(3) (+) to combine with noble gases X has been investigated from neon to xenon using ab initio coupled cluster [CCSD and CCSD(T)] and density functional BH&HLYP levels of theory. For all noble gases, the stable structures belong to a C(2v) symmetry with an apex of the H(3) (+) triangle pointing to the noble gas. The structure of th...
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This study was motivated by the fact that some amino acids are currently identified in carbonaceous chondrites but none are yet observed in the interstellar medium. The question of the relative stability of these prebiotic compounds with respect to the other possible species of the same chemical formula is addressed by means of quantum chemical sim...
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This paper looks at the possibilities opened by reaction of NH with methyl radical. A general survey of the potential surface by ab initio Möller-Plesset (MP2) and density functional theory has been performed, including determination of transition states on the pathways considered and vibrational analysis of all stationary points. Energetical data...
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Noble gases are an important component of the atomic population in the universe. It is generally admitted that these elements are inert and do not participate in molecular structures, except the puzzling X-halides compounds. However, this statement may not be relevant when positive ions are involved, especially is the case of the interstellar mediu...
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The possibility of H3+ playing a role as a sink for noble gases has been investigated in the case of Argon. Elaborate quantum methods (ab initio Coupled Cluster and density functional BH&HLYP levels of theory) have been shown to reproduce the rotational constants within 0.3% together with the only known IR frequency on the test case of Ar…D3+. Diss...
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Observations showing anomalous amounts of noble gas, especially in planetary atmospheres, are at the origin of a series of controversial interpretations from 1990 to nowadays (Hersant et al. (2004)). If, in a first step, we adopt a chemical point of view, we have to consider the possibility of associations of such elements (though usually considere...
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The simplest possible species containing the peptide bond, NH2-CH=O, was identified in space more than thirty years ago (Rubin et al. (1971)). About the same time, a precursor of the peptide bond, HNCO, was also identified (Snyder et al. (1972)) and later confirmed (Brown (1981)) in the interstellar medium (ISM). The same molecule has been recently...
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Since ion-neutral reactions are a major component of the processes driving interstellar chemistry, most reaction network include protonated species. Besides, these ions are able to initiate chemical processes that would not occur with their neutral parents. In this contribution we report a systematic study of the protonated adducts of the OCnO seri...
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In a first approach to the spectral signatures of an irregular carbonaceous matter, we report a theoretical investigation of the infrared spectra of non-regular conjugated hydrocarbons. The series under consideration consists of three-cycle PAHs. Anthracene and phenanthrene are taken as references for regular PAHs and dibenzocyclobutadiene (bipheny...
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Three attractive hypotheses have been proposed to interpret the origin of the satellites of the 3.3-μ m band, and especially the most prominent feature at 3.4 μ m, in connection with polycyclic aromatic hydrocarbons (PAHs): first, the hot bands hypothesis; secondly, the side groups hypothesis; thirdly, the perhydrogenation hypothesis. We considered...
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In this second paper on the 3.2–3.5 μm region, we report the results of a theoretical study of the possible contributions of hydrogenated compounds to the observed infrared emission. We consider small aromatic species to which hydrogens have been added directly on the polycyclic frame, in both neutral and ionized forms, to mimic typical structural...
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Adsorption of atmospheric gases such as NO, NO2, HNO3,.. on various aerosols sur- faces has been mainly pointed out from chamber experiments. Some of these exper- iments allowed to deduce their uptake coefficients which may be dependent on the experimental conditions (time exposure, particle size and concentration, temperature ...). Another approac...
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Fluoren-9-ylidenemethylene-(2,4,6-tri-tert-butyl-phenyl)phosphane (2), a new type of phosphaallene with the terminal carbone incorporated in a cyclopentadienyl ring, has been synthesized and its crystal structure has been determined. The 31P and 13C (central carbon) hyperfine tensors of the reduction compound of this phosphaallene have been measure...
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This paper looks at the possibility of astronomical detection of molecules of prebiotic interest containing phosphorus. Attention has been focused on the most stable species that can be formed with the four [C,H,O,P] atoms. Ab initio coupled cluster molecular orbital methods and density functional theory have been used. It is found that the best ca...
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The structure of van der Waals dimers (N2)2 is studied using ab initio and density functional calculations. The potential energy surfaces corrected a priori for basis set superposition errors are necessary for determining both the geometries and the vibrational frequencies. With both ab initio MP2, MP4 and DFT PW91–PW91 levels of theory, the T-shap...
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Penning ionisation electron spectroscopy (PIES) experiments are reported for acetonitrile (CH3CN), acrylonitrile (CH2CHCN) and polyacrylonitrile films. Self-consistent field/configuration interaction calculations on CH3CN and CH2CHCN using spatially selected localised orbitals show that the major feature of the PIES spectra is ionisation of the nit...
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In view of further application to the study of molecular and atomic sticking on dust particles, we investigated the capability of the "freeze-and-thaw" cycle of the Kohn-Sham equations with constrained electron density (KSCED) to describe potential energy surfaces of weak van der Waals complexes. We report the results obtained for C6H6 ... X (X=O-2...
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We present a general method for extracting the internal space of an arbitrary wave function, exploiting the molecular symmetry. This permits the rewriting of a wave function built with nonorthogonal orbitals as a compact expansion of Slater determinants over orthogonal orbitals. The method is applied to valence bond (VB) and projected unrestricted...
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A posteriori calculations that reproduce already well-documented experiments are shown to be a prerequisite to a priori calculations of unknown spectra. Anticipating the ISO observations to come, we applied this strategy to the prediction of the IR signatures of molecular ions derived from polycyclic aromatic hydrocarbons (PAHs). After calibration...
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Although density functional theory (DFT) is more and more commonly used as a very efficient tool for the study of molecules and bulls. materials, its applications to weakly bonded systems remain rather sparse in the literature, except studies that consider hydrogen bonding. It is, however, elf essential interest to be able to correctly describe wea...