With its large size, dense atmosphere, methane-based hydrological-like cycle, and diverse surface features, the Saturnian moon Titan is one of the most unique of the outer Solar System satellites. Study of the photochemically produced molecules in Titan's atmosphere is critical in order to understand the mechanics of the atmosphere and, by extension, the interactions between atmosphere, surface, and subsurface water ocean. One example is propyne vapor, a photochemically produced species in Titan's upper atmosphere expected to condense in Titan's stratosphere at lower altitudes. Propyne may also be a trace species in Titan's stratospheric co-condensed ice clouds detected by the Cassini Composite InfraRed Spectrometer. Bulk structural characterization of propyne ice is currently incomplete and is lacking in published laboratory Raman spectra and X-ray diffraction data. Here, we present a laboratory characterization of propyne ice, including the first published X-ray diffraction and Raman spectroscopy results for propyne ice.
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http://dx.doi.org/10.1021/acsearthspacechem.3c00303 | DOI Listing |
Phys Chem Chem Phys
December 2024
Sorbonne Université, CNRS, De la Molécule aux Nano-Objets: Réactivité, Interactions, Spectroscopies, MONARIS, Paris, 75005, France.
The distribution of isomeric species in the interstellar medium cannot be directly related to their relative energetic stabilities but more to their mechanisms of formation and evolution. The abundances of the three isomers of CHO, cyclopropenone, propynal and propadienone, are an example among many other interstellar species wherein kinetic effects control their presence in astrophysical regions. To date, only propynal and cyclopropenone, the two less stable isomers of propadienone, have been detected in the interstellar medium.
View Article and Find Full Text PDFACS Earth Space Chem
May 2024
NASA Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109, United States.
With its large size, dense atmosphere, methane-based hydrological-like cycle, and diverse surface features, the Saturnian moon Titan is one of the most unique of the outer Solar System satellites. Study of the photochemically produced molecules in Titan's atmosphere is critical in order to understand the mechanics of the atmosphere and, by extension, the interactions between atmosphere, surface, and subsurface water ocean. One example is propyne vapor, a photochemically produced species in Titan's upper atmosphere expected to condense in Titan's stratosphere at lower altitudes.
View Article and Find Full Text PDFPhys Chem Chem Phys
March 2019
W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA.
Pure methane (CH4) ices processed by energetic electrons under ultra-high vacuum conditions to simulate secondary electrons formed via galactic cosmic rays (GCRs) penetrating interstellar ice mantles have been shown to produce an array of complex hydrocarbons with the general formulae: CnH2n+2 (n = 4-8), CnH2n (n = 3-9), CnH2n-2 (n = 3-9), CnH2n-4 (n = 4-9), and CnH2n-6 (n = 6-7). By monitoring the in situ chemical evolution of the ice combined with temperature programmed desorption (TPD) studies and tunable single photon ionization coupled to a reflectron time-of-flight mass spectrometer, specific isomers of C3H4, C3H6, C4H4, and C4H6 were probed. These experiments confirmed the synthesis of methylacetylene (CH3CCH), propene (CH3CHCH2), cyclopropane (c-C3H6), vinylacetylene (CH2CHCCH), 1-butyne (HCCC2H5), 2-butyne (CH3CCCH3), 1,2-butadiene (H2CCCH(CH3)), and 1,3-butadiene (CH2CHCHCH2) with yields of 2.
View Article and Find Full Text PDFAstrobiology
June 2015
Astrochemistry Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland.
The strong oxidant H2O2 is known to exist in solid form on Europa and is suspected to exist on several other Solar System worlds at temperatures below 200 K. However, little is known of the thermal chemistry that H2O2 might induce under these conditions. Here, we report new laboratory results on the reactivity of solid H2O2 with eight different compounds in H2O-rich ices.
View Article and Find Full Text PDFExperiments designed to simulate the low temperature surface chemistry occurring in interstellar clouds provide clear evidence of a reaction between oxygen atoms and propyne ice. The reactants are dosed onto a surface held at a fixed temperature between 14 and 100 K. After the dosing period, temperature programmed desorption (TPD), coupled with time-of-flight mass spectrometry, are used to identify two reaction products with molecular formulae C3H4O and C3H4O2.
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