Influence of trace aromatics on the chemical growth mechanisms of Titan aerosol analogues

Gautier, Thomas; Sebree, Joshua A.; Li, Xiang; Pinnick, V.; Grubisic, Andrej; Loeffler, M. J.; Getty, Stéphanie; Trainer, M. G.; Brinckerhoff, W. B.

doi:10.1016/j.pss.2017.03.012

Cited by 31 publications

(40 citation statements)

References 41 publications

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“…In addition, with N2 in the initial gas mixture, several new gas products are nitrogen-containing species. The new gas products are indicative of the composition of the solid haze particles; the formation of nitrogen-containing molecules in the gas phase suggests that nitrogen may also be incorporated into solid particles (Imanaka & Smith 2010, He & Smith 2013, 2014Carrasco et al 2015;Sebree et al 2016;Hicks et al 2016;Gautier et al 2017;Hörst et al 2018b;Berry et al 2019aBerry et al , 2019bUgelow et al 2020). Gas molecules will be easier to detect than complex haze compositions with remote sensing techniques.…”

Section: Mass Spectra Of Gas Phase Productsmentioning

confidence: 99%

“…As shown in Figure 4, the 1000× metallicity case contains higher concentration of CO (14% versus 3.5%), and two extra gases (CO2 and N2). CO2 and extra CO can provide more carbon sources for producing organic hazes, while nitrogen from N2 could be also incorporated into the solid haze particles (Imanaka & Smith 2010, He & Smith 2013, 2014Carrasco et al 2015;Sebree et al 2016;Hicks et al 2016;Gautier et al 2017;Hörst et al 2018b). There is less H2 (43% versus 76%) in the 1000× metallicity case, but the fraction is still more than sufficient to provide a reducing environment in which (He et al 2020, Reed et al 2020 show that small amount of H2S could enhance haze production rate significantly.…”

Section: Haze Production Ratementioning

confidence: 99%

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Sulfur-driven haze formation in warm CO2-rich exoplanet atmospheres

He¹,

Hörst²,

Lewis³

et al. 2020

Nat Astron

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Sulfur gases significantly affect the photochemistry of planetary atmospheres in ourSolar System, and are expected to be important components in exoplanet atmospheres. However, sulfur photochemistry in the context of exoplanets is poorly understood due to a lack of chemical-kinetics information for sulfur species under relevant conditions.Here, we study the photochemical role of hydrogen sulfide (H2S) in warm CO2-rich exoplanet atmospheres (800 K) by carrying out laboratory simulations. We find that H2S plays a significant role in photochemistry, even when present in the atmosphere at relatively low concentrations (1.6%). It participates in both gas and solid phase chemistry, leading to the formation of other sulfur gas products (CH3SH/SO, C2H4S/OCS, SO2/S2, and CS2) and to an increase in solid haze particle production and compositional complexity. Our study shows that we may expect thicker haze with small particle sizes (20 to 140 nm) for warm CO2-rich exoplanet atmospheres that possess H2S.Observations 1-5 and laboratory simulations 6,7 have shown that clouds and/or hazes are likely ubiquitous in the atmospheres of exoplanets. These clouds and hazes play an important role in exoplanet atmospheres and affect the spectra of planets, therefore impacting our ability to observe their atmosphere and assess their habitability. Although a variety of atmospheric gases can condense at specific temperature and pressure conditions to form clouds, haze particles may be produced photochemically over a range of temperatures, pressures, and atmospheric compositions. 6−9 Among the various atmospheric components, sulfur gases significantly influence the photochemistry and haze formation in the atmospheres of Solar System bodies, such as Earth, Venus 10,11 , Jupiter 12,13 , and its moon, Io.

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Section: Mass Spectra Of Gas Phase Productsmentioning

confidence: 99%

Section: Haze Production Ratementioning

confidence: 99%

Sulfur-driven haze formation in warm CO2-rich exoplanet atmospheres

He¹,

Hörst²,

Lewis³

et al. 2020

Nat Astron

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“…Different ionization methods can be used for the analysis of molecules in their solid state, especially Laser Desorption Ionization (LDI). LDI-MS has already been used for the analysis of tholins (Gautier et al, 2017;Imanaka et al, 2004;Mahjoub et al, 2016;Sagan et al, 1993;Somogyi et al, 2012). It has also been used for the analysis of asphaltenes, a fraction of petroleum non-soluble in pentane or heptane (Pereira et al, 2014;Sagan et al, 1993;Tanaka et al, 2004).…”

Section: Mass Spectrometry Analysesmentioning

confidence: 99%

Comparison of soluble and insoluble organic matter in analogues of Titan's aerosols

Maillard

Carrasco

Schmitz-Afonso

et al. 2018

Earth and Planetary Science Letters

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Titan, the biggest moon of Saturn, has a thick atmosphere which presents similarities with the one thought to be on Earth at its beginning. The study of Titan's photochemical haze is thus a precious tool in gaining knowledge of the primitive atmosphere of Earth. The chemistry occurring in Titan's atmosphere and the exact processes at act in the formation of the hazes remain largely unknown. The production of analogs samples on Earth has proved to be a useful tool to improve our knowledge of the aerosols formation on Titan. Such solid organic analogs samples, named tholins, were produced with the PAMPRE experiment (French acronym for Aerosols Microgravity Production by Reactive Plasma). PAMPRE tholins were found to be mostly insoluble, with only one-third of the bulk sample that can be dissolved in methanol. This partial solubility limited the previous studies in mass spectrometry, which were done only on the soluble fraction. The goal of the present study is to compare the two fractions of PAMPRE's tholins (insoluble and soluble) using a ultra-high resolution Fourier transform ion cyclotron resonance mass spectrometer (FTICR) equipped with a laser desorption/ionization source. Using modified Van Krevelen diagrams, we compare the global distribution of the molecules within the samples according to their Hydrogen/Carbon ratio and Nitrogen/Carbon ratio. Major differences are observed in the molecular composition of the soluble and the insoluble fraction. The soluble fraction of tholins was previously identified as a set of polymers of average formula (C 2 H 3 N) n . In this work we observe that the insoluble fraction of tholins is comprised of a significantly different set of polymers with an average composition of (C 4 H 3 N 2 ) n .

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“…1/ A recent simulation study on the fundamental fingerprints (ν 0-1 ) of 51 pure PAHs has shown the spectral region between 730-910 cm -1 corresponds to out-of-plane CH bending at the edge of the aromatic cycle (Tommasini et al, 2016) , 2/ Overtone signatures are due to the n harmonic of the fundamental vibrational state (ν 0-1 ) of a molecule, corresponding to the ν 0-n transition (Kendall 1966, Young et al, 1951 , 3/ The frequencies of overtones do not correspond exactly to n-times the frequency of the fundamental vibration, but rather are expected to show some shift toward lower wavenumber due to the anharmonicity of molecules (Herzberg 1950), And, 4/ Gautier et al (2017) also reported the detection of polymeric patterns in the mass spectra of tholins produced with gas mixture of nitrogen, methane and one or two rings aromatics. These were interpreted as a possible signature of aromatic functions within the structure of tholins produced in such gas mixture.…”

Section: Aerosol Spectral Signaturementioning

confidence: 99%

Detection Opportunity for Aromatic Signature in Titan’s Aerosols in the 4.1–5.3 μm Range

Mathé¹,

Gautier²,

Trainer

et al. 2018

ApJL

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The Cassini/Huygens mission provided new insights on the chemistry of the upper atmosphere of Titan. The presence of large molecules and ions (>100's of amu) detected by Cassini at high altitude was not expected, and questions the original assumptions regarding the aerosol formation pathways. From recent laboratory studies, it has been shown that the inclusion of trace amounts of aromatic species drastically impacts the chemistry of aerosol formation and induces observable changes in the properties of the aerosols. In the present work we focus on the effect of one of the simplest nitrogenous aromatics, pyridine (C 5 H 5 N), on the infrared signature of Titan's aerosol analogs. We introduce initial gas mixtures of: (i) N 2 -C 5 H 5 N (100%/250ppm), (ii) N 2 -CH 4 -C 5 H 5 N (99%/1%/250ppm), (iii) N 2 -CH 4 (99%/1%) in a cold plasma discharge. The material produced, herein called tholins, is then analyzed by mid-infrared spectroscopy. When adding pyridine in the discharge, the tholins produced present an aromatic signature in the 4.1-5.3 µm (1850-2450 cm -1 ) spectral region, attributed to overtones of aromatic C-H out-of-plane bending vibrations. We also observe a spectral shift of the nitrile and iso-nitrile absorption band with the inclusion of pyridine in the gas mixture. These results could help to investigate the data obtained at Titan by the Cassini/VIMS instrument in the 1-5 µm infrared window.

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Influence of trace aromatics on the chemical growth mechanisms of Titan aerosol analogues

Cited by 31 publications

References 41 publications

Sulfur-driven haze formation in warm CO2-rich exoplanet atmospheres

Sulfur-driven haze formation in warm CO2-rich exoplanet atmospheres

Comparison of soluble and insoluble organic matter in analogues of Titan's aerosols

Detection Opportunity for Aromatic Signature in Titan’s Aerosols in the 4.1–5.3 μm Range

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