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Title: Propane Clusters in Titan's Lower Atmosphere: Insights from a Combined Theory/Laboratory Study

Abstract

In spite of the considerable advances made by Cassini–Huygens in our understanding of Titan,many questions endure. In particular, the detailed processes that lead to the formation ofhaze aerosols in Titan’s atmosphere, found in high concentrations at low altitudes, are notwell identified. Hydrocarbons, which are abundant constituents of Titan’s cold atmosphereoriginating from photochemical processes, may simultaneously condense on the surface ofexisting aerosols, nucleate and grow to generate new aerosol seeds. The relative importance ofthe various processes depends on several factors, including the saturation ratio. The dynamicsof hydrocarbon condensation and nucleation in Titan’s atmosphere remains poorly known.Aiming to progress on these issues, we investigate here the kinetics of propane dimer formationat low temperature through state-of-the-art laboratory experiments combined with theoreticalcalculations. Our results provide an estimate of the rate coefficients, which are then employedto evaluate the abundance of propane dimers in the lower atmosphere of Titan. The mixingratios of propane dimers inferred, with a maximum abundance of 10 cm−3near 100 km, isfound to be under the detection limit of the Composite Infrared Spectrometer of the Cassinispacecraft. Based on our results, homogeneous nucleation of the most abundant species appearsnot to be relevant for the growth of aerosols. Future studies should focus on homogeneousnucleation ofmore » polar molecules or alternatively on heterogeneous processes, which are usuallymore efficient.« less

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
Centre National de la Recherche Scientifique (CNRS); USDOE Office of Science - Office of Basic Energy Sciences - Chemical Sciences, Geosciences, and Biosciences Division
OSTI Identifier:
1550807
DOE Contract Number:  
AC02-06CH11357
Resource Type:
Journal Article
Journal Name:
Monthly Notices of the Royal Astronomical Society
Additional Journal Information:
Journal Volume: 488
Country of Publication:
United States
Language:
English
Subject:
Titan's atmosphere; aerosols; molecular proccesses; nucleation

Citation Formats

Bourgalais, J., Durif, O., Le Picard, S. D., Lavvas, P., Calvo, F., Klippenstein, S. J., and Biennier, L. Propane Clusters in Titan's Lower Atmosphere: Insights from a Combined Theory/Laboratory Study. United States: N. p., 2019. Web. doi:10.1093/mnras/stz1743.
Bourgalais, J., Durif, O., Le Picard, S. D., Lavvas, P., Calvo, F., Klippenstein, S. J., & Biennier, L. Propane Clusters in Titan's Lower Atmosphere: Insights from a Combined Theory/Laboratory Study. United States. doi:10.1093/mnras/stz1743.
Bourgalais, J., Durif, O., Le Picard, S. D., Lavvas, P., Calvo, F., Klippenstein, S. J., and Biennier, L. Wed . "Propane Clusters in Titan's Lower Atmosphere: Insights from a Combined Theory/Laboratory Study". United States. doi:10.1093/mnras/stz1743.
@article{osti_1550807,
title = {Propane Clusters in Titan's Lower Atmosphere: Insights from a Combined Theory/Laboratory Study},
author = {Bourgalais, J. and Durif, O. and Le Picard, S. D. and Lavvas, P. and Calvo, F. and Klippenstein, S. J. and Biennier, L.},
abstractNote = {In spite of the considerable advances made by Cassini–Huygens in our understanding of Titan,many questions endure. In particular, the detailed processes that lead to the formation ofhaze aerosols in Titan’s atmosphere, found in high concentrations at low altitudes, are notwell identified. Hydrocarbons, which are abundant constituents of Titan’s cold atmosphereoriginating from photochemical processes, may simultaneously condense on the surface ofexisting aerosols, nucleate and grow to generate new aerosol seeds. The relative importance ofthe various processes depends on several factors, including the saturation ratio. The dynamicsof hydrocarbon condensation and nucleation in Titan’s atmosphere remains poorly known.Aiming to progress on these issues, we investigate here the kinetics of propane dimer formationat low temperature through state-of-the-art laboratory experiments combined with theoreticalcalculations. Our results provide an estimate of the rate coefficients, which are then employedto evaluate the abundance of propane dimers in the lower atmosphere of Titan. The mixingratios of propane dimers inferred, with a maximum abundance of 10 cm−3near 100 km, isfound to be under the detection limit of the Composite Infrared Spectrometer of the Cassinispacecraft. Based on our results, homogeneous nucleation of the most abundant species appearsnot to be relevant for the growth of aerosols. Future studies should focus on homogeneousnucleation of polar molecules or alternatively on heterogeneous processes, which are usuallymore efficient.},
doi = {10.1093/mnras/stz1743},
journal = {Monthly Notices of the Royal Astronomical Society},
number = ,
volume = 488,
place = {United States},
year = {2019},
month = {6}
}