skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Low-temperature formation of polycyclic aromatic hydrocarbons in Titan’s atmosphere

Journal Article · · Nature Astronomy
 [1];  [1]; ORCiD logo [2];  [2]; ORCiD logo [2];  [3];  [3];  [3];  [4]
  1. Univ. of Hawaii at Manoa, Honolulu, HI (United States)
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  3. Samara Univ. (Russian Federation)
  4. Samara Univ. (Russian Federation); Florida International Univ., Miami, FL (United States)

The detection of benzene in Titan’s atmosphere led to the emergence of polycyclic aromatic hydrocarbons (PAHs) as potential nucleation agents triggering the growth of Titan’s orange-brownish haze layers. However, the fundamental mechanisms leading to the formation of PAHs in Titan’s low-temperature atmosphere have remained elusive. We provide persuasive evidence through laboratory experiments and computations that prototype PAHs like anthracene and phenanthrene (C14H10) are synthesized via barrierless reactions involving naphthyl radicals (C10H7•) with vinylacetylene (CH2=CH–C≡CH) in low-temperature environments. These elementary reactions are rapid, have no entrance barriers, and synthesize anthracene and phenanthrene via van der Waals complexes and submerged barriers. This facile route to anthracene and phenanthrene—potential building blocks to complex PAHs and aerosols in Titan—signifies a critical shift in the perception that PAHs can only be formed under high-temperature conditions, providing a detailed understanding of the chemistry of Titan’s atmosphere by untangling elementary reactions on the most fundamental level.

Research Organization:
Univ. of Hawaii at Manoa, Honolulu, HI (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences, and Biosciences Division; Ministry of Education and Science of the Russian Federation
Grant/Contract Number:
FG02-03ER15411; FG02-04ER15570; AC02-05CH11231; 14.Y26.31.0020
OSTI ID:
1603089
Alternate ID(s):
OSTI ID: 1608262
Journal Information:
Nature Astronomy, Vol. 2, Issue 12; ISSN 2397-3366
Publisher:
Springer NatureCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 58 works
Citation information provided by
Web of Science

References (60)

Large Abundances of Polycyclic Aromatic Hydrocarbons in Titan'S Upper Atmosphere journal June 2013
The properties of a micro-reactor for the study of the unimolecular decomposition of large molecules journal September 2014
A VUV Photoionization Study of the Formation of the Indene Molecule and Its Isomers journal June 2011
Kinetic modeling of soot formation with detailed chemistry and physics: laminar premixed flames of C2 hydrocarbons journal April 2000
Density Functional Theory Study of the Formation of Naphthalene and Phenanthrene from Reactions of Phenyl with Vinyl- and Phenylacetylene journal December 2006
Hydrogen Abstraction/Acetylene Addition Revealed journal June 2014
Properties of the main high Molecular Weight Hydrocarbons in Titan'S Atmosphere journal March 1997
Thermodynamic and kinetic issues in the formation and oxidation of aromatic species journal November 2001
Selective Formation of Indene through the Reaction of Benzyl Radicals with Acetylene journal April 2015
Chemical sources of haze formation in Titan's atmosphere journal December 2003
Hydrogen-Abstraction/Acetylene-Addition Exposed journal October 2016
Nitrile gas chemistry in Titan’s atmosphere journal June 2011
H-Atom Yields from the Photolysis of Acetylene and from the Reaction of C 2 H with H 2 , C 2 H 2 , and C 2 H 4 journal April 2010
Study of Titan’s fall southern stratospheric polar cloud composition with Cassini/CIRS: Detection of benzene ice journal August 2018
Composition and chemistry of Titan's thermosphere and ionosphere
  • Vuitton, V.; Yelle, R. V.; Lavvas, P.
  • Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, Vol. 367, Issue 1889 https://doi.org/10.1098/rsta.2008.0233
journal November 2008
A VUV Photoionization Study of the Combustion-Relevant Reaction of the Phenyl Radical (C 6 H 5 ) with Propylene (C 3 H 6 ) in a High Temperature Chemical Reactor journal March 2012
Dependence of two-photon ionization photoelectron spectra on laser coherence bandwidth journal November 1993
Low temperature formation of naphthalene and its role in the synthesis of PAHs (Polycyclic Aromatic Hydrocarbons) in the interstellar medium journal December 2011
Chemical composition of simulated Titan's midatmospheric aerosols journal January 2010
Analysis of Titan's neutral upper atmosphere from Cassini Ion Neutral Mass Spectrometer measurements journal April 2009
HACA's Heritage: A Free-Radical Pathway to Phenanthrene in Circumstellar Envelopes of Asymptotic Giant Branch Stars journal March 2017
Analysis of Cassini/CIRS limb spectra of Titan acquired during the nominal mission journal February 2010
Hydrogen-Abstraction/Acetylene-Addition Exposed journal October 2016
New benzene absorption cross sections in the VUV, relevance for Titan’s upper atmosphere journal February 2016
The role of benzene photolysis in Titan haze formation journal May 2014
Titan's surface reviewed: the nature of bright and dark terrain journal August 1997
Formation of polycyclic aromatic hydrocarbons in circumstellar envelopes journal June 1989
Extremely Slowly Desorbing Polycyclic Aromatic Hydrocarbons from Soot and Soot-like Materials:  Evidence by Supercritical Fluid Extraction journal October 2005
Photochemistry of Benzylallene: Ring-Closing Reactions to Form Naphthalene journal December 2011
Comparative study on the growth mechanisms of PAHs journal February 2011
The photochemical model of Titan’s atmosphere and ionosphere: A version without hydrodynamic escape journal October 2010
Combustion chemistry probed by synchrotron VUV photoionization mass spectrometry journal January 2013
IDENTIFYING THE LOCATION IN THE HOST GALAXY OF THE SHORT GRB 111117A WITH THE CHANDRA SUBARCSECOND POSITION journal March 2013
Two-laser photoionization supersonic jet mass spectrometry of aromatic molecules journal January 1988
Titan’s atmosphere from ISO mid-infrared spectroscopy journal February 2003
Crossed beam investigation of elementary reactions relevant to the formation of polycyclic aromatic hydrocarbon (PAH)-like molecules in extraterrestrial environments journal April 2000
Mechanisms of formation of nitrogen-containing polycyclic aromatic compounds in low-temperature environments of planetary atmospheres: A theoretical study journal January 2010
Polycyclic aromatic hydrocarbons in the atmospheres of Titan and Jupiter journal September 1993
Photoionization mass spectrometer for studies of flame chemistry with a synchrotron light source journal September 2005
Reformulation and Solution of the Master Equation for Multiple-Well Chemical Reactions journal May 2013
Crossed Molecular Beams Study on the Formation of Vinylacetylene in Titan’s Atmosphere journal October 2009
Theoretical Study of Potential Energy Surface and Thermal Rate Constants for the C 6 H 5 + H 2 and C 6 H 6 + H Reactions journal April 1997
Temperature- and pressure-dependent rate coefficients for the HACA pathways from benzene to naphthalene journal January 2017
Hydrogen Abstraction/Acetylene Addition Revealed journal June 2014
Gaussian-3 theory using coupled cluster energies journal November 1999
Formation Mechanisms of Naphthalene and Indene: From the Interstellar Medium to Combustion Flames journal January 2017
The composition of Titan's stratosphere from Cassini/CIRS mid-infrared spectra journal July 2007
Unexpected Chemistry from the Reaction of Naphthyl and Acetylene at Combustion-Like Temperatures journal March 2015
Formation of nitrogenated organic aerosols in the Titan upper atmosphere journal July 2010
Gaussian-3 (G3) theory for molecules containing first and second-row atoms journal November 1998
Gaussian-3 theory using density functional geometries and zero-point energies journal April 1999
The photochemical products of benzene in Titan’s upper atmosphere journal May 2010
Organic chemistry in Titan׳s upper atmosphere and its astrobiological consequences: I. Views towards Cassini plasma spectrometer (CAPS) and ion neutral mass spectrometer (INMS) experiments in space journal May 2015
Whole mantle P wave tomography using P and PP-P data: P WAVE TOMOGRAPHY USING P AND PP-P DATA journal January 2003
A modelling study of aromatic soot precursors formation in laminar methane and ethene flames journal September 2009
Kinetic Pathways in the Atmospheric Chemistry of Titan – a Generalized Analysis journal March 2004
Unexpected Chemistry from the Reaction of Naphthyl and Acetylene at Combustion-Like Temperatures journal March 2015
HACA's Heritage: A Free-Radical Pathway to Phenanthrene in Circumstellar Envelopes of Asymptotic Giant Branch Stars journal March 2017
Identifying the Location in the Host Galaxy of the Short GRB 111117A with the Chandra Sub-arcsecond Position text January 2012
Study of Titan's fall southern stratospheric polar cloud composition with Cassini/CIRS: detection of benzene ice text January 2018

Cited By (19)

Low-temperature Formation of Carbonaceous Dust Grains from PAHs journal January 2020
Molecular mass growth through ring expansion in polycyclic aromatic hydrocarbons via radical–radical reactions journal August 2019
Directed Gas‐Phase Synthesis of Triafulvene under Single‐Collision Conditions journal October 2019
How to add a five-membered ring to polycyclic aromatic hydrocarbons (PAHs) – molecular mass growth of the 2-naphthyl radical (C 10 H 7 ) to benzindenes (C 13 H 10 ) as a case study journal January 2019
From atoms to aerosols: probing clusters and nanoparticles with synchrotron based mass spectrometry and X-ray spectroscopy journal January 2020
Synthesis of Polycyclic Aromatic Hydrocarbons by Phenyl Addition–Dehydrocyclization: The Third Way journal November 2019
A Unified Mechanism on the Formation of Acenes, Helicenes, and Phenacenes in the Gas Phase journal January 2020
Gas‐Phase Synthesis of Triphenylene (C 18 H 12 ) journal February 2019
Optical band gap of cross-linked, curved, and radical polyaromatic hydrocarbons journal January 2019
NarL, a Novel Repressor for CYP108j1 Expression during PAHs Degradation in Rhodococcus sp. P14 journal February 2020
Dusty Outflows in Planetary Atmospheres: Understanding “Super-puffs” and Transmission Spectra of Sub-Neptunes journal February 2019
Gas‐Phase Synthesis of Triphenylene (C 18 H 12 ) journal March 2019
A Unified Mechanism on the Formation of Acenes, Helicenes, and Phenacenes in the Gas Phase journal March 2020
A new take on circumstellar carbon chemistry journal October 2019
Low-temperature synthesis of polycyclic aromatic hydrocarbons in Titan’s surface ices and on airless bodies journal October 2019
Polycyclic aromatic hydrocarbon formation chemistry in a plasma jet revealed by IR-UV action spectroscopy journal January 2020
Synthesis of Polycyclic Aromatic Hydrocarbons by Phenyl Addition-Dehydrocyclization: The Third Way journal October 2019
Directed Gas‐Phase Synthesis of Triafulvene under Single‐Collision Conditions journal September 2019
A combined experimental and computational study on the reaction dynamics of the 1-propynyl radical (CH 3 CC; X 2 A 1 ) with ethylene (H 2 CCH 2 ; X 1 A 1g ) and the formation of 1-penten-3-yne (CH 2 CHCCCH 3 ; X 1 A′) journal January 2019

Similar Records

Reaction Dynamics in Astrochemistry: Low-Temperature Pathways to Polycyclic Aromatic Hydrocarbons in the Interstellar Medium
Journal Article · Thu Nov 20 00:00:00 EST 2014 · Annual Review of Physical Chemistry · OSTI ID:1603089

A Free-Radical Prompted Barrierless Gas-Phase Synthesis of Pentacene
Journal Article · Tue Apr 07 00:00:00 EDT 2020 · Angewandte Chemie (International Edition) · OSTI ID:1603089

Gas-Phase Synthesis of Triphenylene (C18H12)
Journal Article · Fri Feb 01 00:00:00 EST 2019 · ChemPhysChem · OSTI ID:1603089