Volatile products controlling Titan's tholins production

Handle URI:
http://hdl.handle.net/10754/562168
Title:
Volatile products controlling Titan's tholins production
Authors:
Carrasco, Nathalie; Gautier, Thomas N.; Es-sebbar, Et-touhami; Pernot, Pascal; Cernogora, Guy
Abstract:
A quantitative agreement between nitrile relative abundances and Titan's atmospheric composition was recently shown with a reactor simulating the global chemistry occurring in Titan's atmosphere (Gautier et al. [2011]. Icarus, 213, 625-635). Here we present a complementary study on the same reactor using an in situ diagnostic of the gas phase composition. Various initial N 2/CH 4 gas mixtures (methane varying from 1% to 10%) are studied, with a monitoring of the methane consumption and of the stable gas neutrals by in situ mass spectrometry. Atomic hydrogen is also measured by optical emission spectroscopy. A positive correlation is found between atomic hydrogen abundance and the inhibition function for aerosol production. This confirms the suspected role of hydrogen as an inhibitor of heterogeneous organic growth processes, as found in Sciamma-O'Brien et al. (Sciamma-O'Brien et al. [2010]. Icarus, 209, 704-714). The study of the gas phase organic products is focussed on its evolution with the initial methane amount [CH 4] 0 and its comparison with the aerosol production efficiency. We identify a change in the stationary gas phase composition for intermediate methane amounts: below [CH 4] 0=5%, the gas phase composition is mainly dominated by nitrogen-containing species, whereas hydrocarbons are massively produced for [CH 4] 0>5%. This predominance of N-containing species at lower initial methane amount, compared with the maximum gas-to solid conversion observed in Sciamma-O'Brien et al. (2010) for identical methane amounts confirms the central role played by N-containing gas-phase compounds to produce tholins. Moreover, two protonated imines (methanimine CH 2NH and ethanamine CH 3CHNH) are detected in the ion composition in agreement with Titan's INMS measurements, and reinforcing the suspected role of these chemical species on aerosol production. © 2012 Elsevier Inc.
KAUST Department:
Clean Combustion Research Center
Publisher:
Elsevier BV
Journal:
Icarus
Issue Date:
May-2012
DOI:
10.1016/j.icarus.2012.02.034
Type:
Article
ISSN:
00191035
Appears in Collections:
Articles; Clean Combustion Research Center

Full metadata record

DC FieldValue Language
dc.contributor.authorCarrasco, Nathalieen
dc.contributor.authorGautier, Thomas N.en
dc.contributor.authorEs-sebbar, Et-touhamien
dc.contributor.authorPernot, Pascalen
dc.contributor.authorCernogora, Guyen
dc.date.accessioned2015-08-03T09:46:21Zen
dc.date.available2015-08-03T09:46:21Zen
dc.date.issued2012-05en
dc.identifier.issn00191035en
dc.identifier.doi10.1016/j.icarus.2012.02.034en
dc.identifier.urihttp://hdl.handle.net/10754/562168en
dc.description.abstractA quantitative agreement between nitrile relative abundances and Titan's atmospheric composition was recently shown with a reactor simulating the global chemistry occurring in Titan's atmosphere (Gautier et al. [2011]. Icarus, 213, 625-635). Here we present a complementary study on the same reactor using an in situ diagnostic of the gas phase composition. Various initial N 2/CH 4 gas mixtures (methane varying from 1% to 10%) are studied, with a monitoring of the methane consumption and of the stable gas neutrals by in situ mass spectrometry. Atomic hydrogen is also measured by optical emission spectroscopy. A positive correlation is found between atomic hydrogen abundance and the inhibition function for aerosol production. This confirms the suspected role of hydrogen as an inhibitor of heterogeneous organic growth processes, as found in Sciamma-O'Brien et al. (Sciamma-O'Brien et al. [2010]. Icarus, 209, 704-714). The study of the gas phase organic products is focussed on its evolution with the initial methane amount [CH 4] 0 and its comparison with the aerosol production efficiency. We identify a change in the stationary gas phase composition for intermediate methane amounts: below [CH 4] 0=5%, the gas phase composition is mainly dominated by nitrogen-containing species, whereas hydrocarbons are massively produced for [CH 4] 0>5%. This predominance of N-containing species at lower initial methane amount, compared with the maximum gas-to solid conversion observed in Sciamma-O'Brien et al. (2010) for identical methane amounts confirms the central role played by N-containing gas-phase compounds to produce tholins. Moreover, two protonated imines (methanimine CH 2NH and ethanamine CH 3CHNH) are detected in the ion composition in agreement with Titan's INMS measurements, and reinforcing the suspected role of these chemical species on aerosol production. © 2012 Elsevier Inc.en
dc.publisherElsevier BVen
dc.subjectAstrobiologyen
dc.subjectAtmospheres, Chemistryen
dc.subjectIonospheresen
dc.subjectTitanen
dc.titleVolatile products controlling Titan's tholins productionen
dc.typeArticleen
dc.contributor.departmentClean Combustion Research Centeren
dc.identifier.journalIcarusen
dc.contributor.institutionLaboratoire Atmosphères Milieux, Observations Spatiales, Université de Versailles Saint-Quentin, UMR 8190, 78280 Guyancourt, Franceen
dc.contributor.institutionLaboratoire de Chimie Physique, UMR 8000, CNRS, Univ Paris-Sud, 91405 Orsay cedex, Franceen
kaust.authorEs-sebbar, Et-touhamien
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