The influence of methane, acetylene and carbon dioxide on the crystallization of supercooled ethane droplets in Titan's clouds

Lang, E. Kathrin; Knox, Kerry J.; Wang, Chia C.; Signorell, Ruth

doi:10.1016/j.pss.2011.02.009

Cited by 10 publications

(22 citation statements)

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“…Furthermore, ethane has been detected on the surfaces of Makemake (Brown et al 2007), Quaoar (Schaller & Brown 2007), and KBO 1993SC, with the evidence for 1993SC and Quaoar implying hitherto unidentified higher order hydrocarbons to be present as well (Brown et al 1997). Finally, ethane is also of potential relevance to Saturn's moon Titan in the form of solid ethane ice droplets (Lang et al 2011). In 2009, Bauerecker & Dartois ( 2009) simulated the growth of ethane aerosols in the laboratory, demonstrating that gaseous ethane condenses first in its liquid phase and then grows to micrometersized droplets accompanied by morphological changes toward crystalline solids.…”

Section: Astrophysical Implicationsmentioning

confidence: 92%

On the Radiolysis of Ethylene Ices by Energetic Electrons and Implications to the Extraterrestrial Hydrocarbon Chemistry

Zhou

Maity

Abplanalp

et al. 2014

ApJ

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The chemical processing of ethylene ices (C 2 H 4 ) by energetic electrons was investigated at 11 K to simulate the energy transfer processes and synthesis of new molecules induced by secondary electrons generated in the track of galactic cosmic ray particles. A combination of Fourier transform infrared spectrometry (solid state) and quadrupole mass spectrometry (gas phase) resulted in the identification of six hydrocarbon molecules: methane (CH 4 ), the C2 species acetylene (C 2 H 2 ), ethane (C 2 H 6 ), the ethyl radical (C 2 H 5 ), and-for the very first time in ethylene irradiation experiments-the C4 hydrocarbons 1-butene (C 4 H 8 ) and n-butane (C 4 H 10 ). By tracing the temporal evolution of the newly formed molecules spectroscopically online and in situ, we were also able to fit the kinetic profiles with a system of coupled differential equations, eventually providing mechanistic information, reaction pathways, and rate constants on the radiolysis of ethylene ices and the inherent formation of smaller (C1) and more complex (C2, C4) hydrocarbons involving carbon-hydrogen bond ruptures, atomic hydrogen addition processes, and radical-radical recombination pathways. We also discuss the implications of these results on the hydrocarbon chemistry on Titan's surface and on ice-coated, methane-bearing interstellar grains as present in cold molecular clouds such as TMC-1.

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Section: Astrophysical Implicationsmentioning

confidence: 92%

On the Radiolysis of Ethylene Ices by Energetic Electrons and Implications to the Extraterrestrial Hydrocarbon Chemistry

Zhou

Maity

Abplanalp

et al. 2014

ApJ

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“…Finally, the experimental temperature range of our current apparatus is limited and spans a range from approximately room temperature (300 K) to 223 K. We would like to extend this from 373 K to as low as 78 K to study single pure and mixedcomponent particles that may be relevant to planetary and lunar atmospheres to complement our previous studies of particle ensembles. [48][49][50][51][68][69][70] Combining the more stable QBB trap and more accurate size determination with white light scattering in an apparatus that has a greater temperature range will provide the tools necessary for these future studies.…”

Section: Discussionmentioning

confidence: 99%

“…We show first examples of homogeneous and heterogeneous freezing, freezingmelting cycles, and evaporation of single particles. In the following work, we explore single, submicrometer-sized water and hydrocarbon aerosols that are stably trapped on the order of hours in a CPBB trap across a wide temperature range (226-330 K) relevant to planetary and lunar atmospheres (e.g., Earth, [44][45][46][47] Mars, 48 Titan [49][50][51] ). Studying finemode (r < 1 μm) water and hydrocarbon aerosols at cold temperatures may help us to better understand, respectively, cirrus clouds that form in the upper troposphere/lower stratosphere, as well as organic aerosols in the lower troposphere with anthropogenic origins.…”

Section: Introductionmentioning

confidence: 99%

Low-temperature Bessel beam trap for single submicrometer aerosol particle studies

Isenor

Chasovskikh

et al. 2014

Review of Scientific Instruments

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We report on a new instrument for single aerosol particle studies at low temperatures that combines an optical trap consisting of two counter-propagating Bessel beams (CPBBs) and temperature control down to 223 K (-50 °C). The apparatus is capable of capturing and stably trapping individual submicrometer- to micrometer-sized aerosol particles for up to several hours. First results from studies of hexadecane, dodecane, and water aerosols reveal that we can trap and freeze supercooled droplets ranging in size from ~450 nm to 5500 nm (radius). We have conducted homogeneous and heterogeneous freezing experiments, freezing-melting cycles, and evaporation studies. To our knowledge, this is the first reported observation of the freezing process for levitated single submicrometer-sized droplets in air using optical trapping techniques. These results show that a temperature-controlled CPBB trap is an attractive new method for studying phase transitions of individual submicrometer aerosol particles.

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“…The setup has been prepared to generate binary-phase CH 3 CN–H 2 O aerosols under conditions simulating the Titan atmosphere. A qualitative and quantitative approach consistent with that reported by Signorell and co-workers ,− was adopted herein, where IR spectra (including far-IR region) were collected to track the formation and depletion of the binary-phase CH 3 CN–H 2 O aerosol population.…”

Section: Methodsmentioning

confidence: 99%

Binary-Phase Acetonitrile and Water Aerosols: Infrared Studies and Theoretical Simulation at Titan Atmosphere Conditions

Auchettl

Ruzi

Appadoo

et al. 2018

ACS Earth Space Chem.

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Acetonitrile (CH3CN) and water (H2O) ice particles were generated within a collisional cooling cell coupled to the Australian Synchrotron light source. The evolution of the aerosols was tracked by infrared spectroscopy compiled over the 4000–50 cm–1 region. Gas pressure and temperature conditions were varied to replicate the lower altitudes of the Titan atmosphere allowing for comparison to far-infrared features detected by the Cassini–Huygens spacecraft. The experimental spectra show that CH3CN and H2O particles are microheterogeneous in composition and spherical in shape. CH3CN lattice bands display temperature-dependent shifts in frequency, implying that pure β-phase is present in the mixed particles. In addition, a red shift identified for the CN fundamental stretching mode indicates dipole–dipole and π-electron side-directed hydrogen bond coupling between segregated CH3CN and H2O phases exclusively at the grain interface. Discrete dipole approximation theory was implemented to evaluate various cluster architectures where segregated domains of pure CH3CN and H2O ices provided the best fit to experiment; confirming the infrared findings. Otherwise, simulations of competing architectures, such as core–shell and cubic shaped particles, did not provide convincing comparison to the aerosol spectra. We conclude that the far-infrared profiles for mixed CH3CN–H2O systems do not present as likely carriers for the unassigned 220 cm–1 “haystack” feature that has been identified in Titan’s lower atmosphere.

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The influence of methane, acetylene and carbon dioxide on the crystallization of supercooled ethane droplets in Titan's clouds

Cited by 10 publications

References 49 publications

On the Radiolysis of Ethylene Ices by Energetic Electrons and Implications to the Extraterrestrial Hydrocarbon Chemistry

On the Radiolysis of Ethylene Ices by Energetic Electrons and Implications to the Extraterrestrial Hydrocarbon Chemistry

Low-temperature Bessel beam trap for single submicrometer aerosol particle studies

Binary-Phase Acetonitrile and Water Aerosols: Infrared Studies and Theoretical Simulation at Titan Atmosphere Conditions

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