The Experts below are selected from a list of 258 Experts worldwide ranked by ideXlab platform
Cyril Szopa - One of the best experts on this subject based on the ideXlab platform.
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Organic chemistry in a CO2 rich early Earth Atmosphere
Earth and Planetary Science Letters, 2017Co-Authors: Benjamin Fleury, Nathalie Carrasco, Maeva Millan, Ludovic Vettier, Cyril SzopaAbstract:The emergence of life on the Earth has required a prior organic chemistry leading to the formation of prebiotic molecules. The origin and the evolution of the organic matter on the early Earth is not yet firmly understood. Several hypothesis, possibly complementary, are considered. They can be divided in two categories: endogenous and exogenous sources. In this work we investigate the contribution of a specific endogenous source: the organic chemistry occurring in the ionosphere of the early Earth where the significant VUV contribution of the young Sun involved an efficient formation of reactive species. We address the issue whether this chemistry can lead to the formation of complex organic compounds with CO2 as only source of carbon in an early Atmosphere made of N2, CO2 and H2, by mimicking experimentally this type of chemistry using a low pressure plasma reactor. By analyzing the gaseous phase composition, we strictly identified the formation of H2O, NH3, N2O and C2N2. The formation of a solid organic phase is also observed, confirming the possibility to trigger organic chemistry in the upper Atmosphere of the early Earth. The identification of Nitrogen-bearing chemical functions in the solid highlights the possibility for an efficient ionospheric chemistry to provide prebiotic material on the early Earth.
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Organic chemistry in a CO 2 rich early Earth Atmosphere
Earth and Planetary Science Letters, 2017Co-Authors: Benjamin Fleury, Nathalie Carrasco, Maeva Millan, Ludovic Vettier, Cyril SzopaAbstract:Abstract The emergence of life on the Earth has required a prior organic chemistry leading to the formation of prebiotic molecules. The origin and the evolution of the organic matter on the early Earth is not yet firmly understood. Several hypothesis, possibly complementary, are considered. They can be divided in two categories: endogenous and exogenous sources. In this work we investigate the contribution of a specific endogenous source: the organic chemistry occurring in the ionosphere of the early Earth where the significant VUV contribution of the young Sun involved an efficient formation of reactive species. We address the issue whether this chemistry can lead to the formation of complex organic compounds with CO2 as only source of carbon in an early Atmosphere made of N2, CO2 and H2, by mimicking experimentally this type of chemistry using a low pressure plasma reactor. By analyzing the gaseous phase composition, we strictly identified the formation of H2O, NH3, N2O and C2N2. The formation of a solid organic phase is also observed, confirming the possibility to trigger organic chemistry in the upper Atmosphere of the early Earth. The identification of Nitrogen-bearing chemical functions in the solid highlights the possibility for an efficient ionospheric chemistry to provide prebiotic material on the early Earth.
Benjamin Fleury - One of the best experts on this subject based on the ideXlab platform.
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Organic chemistry in a CO2 rich early Earth Atmosphere
Earth and Planetary Science Letters, 2017Co-Authors: Benjamin Fleury, Nathalie Carrasco, Maeva Millan, Ludovic Vettier, Cyril SzopaAbstract:The emergence of life on the Earth has required a prior organic chemistry leading to the formation of prebiotic molecules. The origin and the evolution of the organic matter on the early Earth is not yet firmly understood. Several hypothesis, possibly complementary, are considered. They can be divided in two categories: endogenous and exogenous sources. In this work we investigate the contribution of a specific endogenous source: the organic chemistry occurring in the ionosphere of the early Earth where the significant VUV contribution of the young Sun involved an efficient formation of reactive species. We address the issue whether this chemistry can lead to the formation of complex organic compounds with CO2 as only source of carbon in an early Atmosphere made of N2, CO2 and H2, by mimicking experimentally this type of chemistry using a low pressure plasma reactor. By analyzing the gaseous phase composition, we strictly identified the formation of H2O, NH3, N2O and C2N2. The formation of a solid organic phase is also observed, confirming the possibility to trigger organic chemistry in the upper Atmosphere of the early Earth. The identification of Nitrogen-bearing chemical functions in the solid highlights the possibility for an efficient ionospheric chemistry to provide prebiotic material on the early Earth.
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Organic chemistry in a CO 2 rich early Earth Atmosphere
Earth and Planetary Science Letters, 2017Co-Authors: Benjamin Fleury, Nathalie Carrasco, Maeva Millan, Ludovic Vettier, Cyril SzopaAbstract:Abstract The emergence of life on the Earth has required a prior organic chemistry leading to the formation of prebiotic molecules. The origin and the evolution of the organic matter on the early Earth is not yet firmly understood. Several hypothesis, possibly complementary, are considered. They can be divided in two categories: endogenous and exogenous sources. In this work we investigate the contribution of a specific endogenous source: the organic chemistry occurring in the ionosphere of the early Earth where the significant VUV contribution of the young Sun involved an efficient formation of reactive species. We address the issue whether this chemistry can lead to the formation of complex organic compounds with CO2 as only source of carbon in an early Atmosphere made of N2, CO2 and H2, by mimicking experimentally this type of chemistry using a low pressure plasma reactor. By analyzing the gaseous phase composition, we strictly identified the formation of H2O, NH3, N2O and C2N2. The formation of a solid organic phase is also observed, confirming the possibility to trigger organic chemistry in the upper Atmosphere of the early Earth. The identification of Nitrogen-bearing chemical functions in the solid highlights the possibility for an efficient ionospheric chemistry to provide prebiotic material on the early Earth.
B. Marty - One of the best experts on this subject based on the ideXlab platform.
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The I-Pu-Xe age of the Moon-Earth system revisited
Philosophical transactions. Series A Mathematical physical and engineering sciences, 2014Co-Authors: G Avice, B. MartyAbstract:From iodine-plutonium-xenon isotope systematics, we re-evaluate time constraints on the early evolution of the Earth-Atmosphere system and, by inference, on the Moon-forming event. Two extinct radioactivites (129 I, T 1/2 = 15.6 Ma, and 244 Pu, T 1/2 = 80 Ma) have produced radiogenic 129 Xe and fissiogenic 131-136 Xe, respectively, within the Earth, which related isotope fingerprints are seen in the compositions of mantle and atmospheric Xe. Recent studies of Archean rocks suggest that xenon atoms have been lost from the Earth's Atmosphere and isotopically fractionated during long periods of geological time, until at least the end of the Archean eon. Here we build a model that takes into account these results. Correction for Xe loss permits to compute new closure ages for the Earth's Atmosphere that are in agreement with those computed for mantle Xe. The minimum Xe formation interval for the Earth-Atmosphere is 40-10 +20 Ma after start of solar system formation, which may also date the Moon-forming impact.
Jeanphilippe Gastelluetchegorry - One of the best experts on this subject based on the ideXlab platform.
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radiative transfer modeling in the Earth Atmosphere system with dart model
Remote Sensing of Environment, 2013Co-Authors: Eloi Grau, Jeanphilippe GastelluetchegorryAbstract:The Atmosphere strongly affects satellite measurements of Earth surfaces in the optical domain. Modeling this influence is complex. This is typically the case of the “Earth–Atmosphere” radiative coupling in the presence of Earth surfaces with spatially variable optical properties. In that case, it may be very difficult to couple Earth and cloud-free Atmosphere radiative transfer models. This explains why an Atmosphere module was input into the Earth radiative transfer (R.T.) model DART (Discrete Anisotropic Radiative Transfer) in order to simulate accurately satellite images of natural and urban Earth surfaces. This paper presents how DART simulates the Atmosphere R.T. in the short wave and thermal infrared domains. The Atmosphere is divided into 3 zones: bottom Atmosphere (BA), mid Atmosphere (MA) and high Atmosphere (HA). The 3D distribution is arbitrary in BA and horizontally constant with any vertical distribution in MA and HA. The “Earth–Atmosphere” R.T. is modeled in 5 stages. 1) Atmosphere R.T. (i.e., Atmosphere thermal emission and/or sun radiation scattering). 2) Earth surface R.T. (i.e., Earth thermal emission and/or Atmosphere and direct sun radiation scattering). 3) Atmosphere R.T. (i.e., Earth radiation scattering). 4) Earth surface R.T. (i.e., scattering of downward Atmosphere radiation). 5) Simulation of satellite reflectance and/or brightness temperature images. The approach takes into account the Earth curvature and the Atmosphere non-Beer law behavior in the presence of strongly varying spectral properties. It uses optimally located scattering points for improving Atmosphere R.T. accuracy, and it reduces computer time through the use of pre-computed transfer functions that transfer radiation between the different Atmosphere levels (BA, MA, HA). Moreover, it can simulate automatically an Atmosphere geometry that optimizes the trade-off “Computer time–Accuracy” of simulations. The robustness and accuracy of the DART Atmosphere modeling were successfully validated with theoretical cases and with the MODTRAN Atmosphere R.T. model.
Nathalie Carrasco - One of the best experts on this subject based on the ideXlab platform.
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Organic chemistry in a CO2 rich early Earth Atmosphere
Earth and Planetary Science Letters, 2017Co-Authors: Benjamin Fleury, Nathalie Carrasco, Maeva Millan, Ludovic Vettier, Cyril SzopaAbstract:The emergence of life on the Earth has required a prior organic chemistry leading to the formation of prebiotic molecules. The origin and the evolution of the organic matter on the early Earth is not yet firmly understood. Several hypothesis, possibly complementary, are considered. They can be divided in two categories: endogenous and exogenous sources. In this work we investigate the contribution of a specific endogenous source: the organic chemistry occurring in the ionosphere of the early Earth where the significant VUV contribution of the young Sun involved an efficient formation of reactive species. We address the issue whether this chemistry can lead to the formation of complex organic compounds with CO2 as only source of carbon in an early Atmosphere made of N2, CO2 and H2, by mimicking experimentally this type of chemistry using a low pressure plasma reactor. By analyzing the gaseous phase composition, we strictly identified the formation of H2O, NH3, N2O and C2N2. The formation of a solid organic phase is also observed, confirming the possibility to trigger organic chemistry in the upper Atmosphere of the early Earth. The identification of Nitrogen-bearing chemical functions in the solid highlights the possibility for an efficient ionospheric chemistry to provide prebiotic material on the early Earth.
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Organic chemistry in a CO 2 rich early Earth Atmosphere
Earth and Planetary Science Letters, 2017Co-Authors: Benjamin Fleury, Nathalie Carrasco, Maeva Millan, Ludovic Vettier, Cyril SzopaAbstract:Abstract The emergence of life on the Earth has required a prior organic chemistry leading to the formation of prebiotic molecules. The origin and the evolution of the organic matter on the early Earth is not yet firmly understood. Several hypothesis, possibly complementary, are considered. They can be divided in two categories: endogenous and exogenous sources. In this work we investigate the contribution of a specific endogenous source: the organic chemistry occurring in the ionosphere of the early Earth where the significant VUV contribution of the young Sun involved an efficient formation of reactive species. We address the issue whether this chemistry can lead to the formation of complex organic compounds with CO2 as only source of carbon in an early Atmosphere made of N2, CO2 and H2, by mimicking experimentally this type of chemistry using a low pressure plasma reactor. By analyzing the gaseous phase composition, we strictly identified the formation of H2O, NH3, N2O and C2N2. The formation of a solid organic phase is also observed, confirming the possibility to trigger organic chemistry in the upper Atmosphere of the early Earth. The identification of Nitrogen-bearing chemical functions in the solid highlights the possibility for an efficient ionospheric chemistry to provide prebiotic material on the early Earth.
