The neutral photochemistry of nitriles, amines and imines in the atmosphere of Titan

The photochemistry of N2 and CH4 in the atmosphere of Titan leads to a very rich chemistry which is not well understood. The aim of our study is to improve our understanding of the production of nitrogen compounds and to predict the abundances of those with high molar mass with better accuracy. We have made a careful investigation of the neutral nitrogen photochemistry to improve current chemical schemes including the most abundant species and the most efficient reactions. We also studied the propagation of uncertainties on rate constants in our model and determined the key reactions from a global sensitivity analysis. Our photochemical model contains 124 species, 60 of which are nitrogen containing compounds, and 1141 reactions. Our results are in reasonable agreement with Cassini/INMS data in the higher atmosphere but our model overestimates the mole fractions of several nitriles in the lower stratosphere. New species such as CH3C3N and C3H7CN could be relatively abundant in Titan's atmosphere. Uncertainties on some nitrogen compounds are important and further studies of the key reactions that we have identified are needed to improve the predictivity of photochemical models. Meridional transport is expected to be an efficient process to govern the abundances of several nitriles in the lower stratosphere.

[1]  E. P. Hunter,et al.  Evaluated Gas Phase Basicities and Proton Affinities of Molecules: An Update , 1998 .

[2]  B. Bussery-Honvault,et al.  Towards a converged barrier height for the entrance channel transition state of the N(2D) + CH4 reaction and its implication for the chemistry in Titan’s atmosphere , 2011 .

[3]  Roger V. Yelle,et al.  Methane escape from Titan's atmosphere , 2008 .

[4]  D. Strobel,et al.  New perspectives on Titan's upper atmosphere from a reanalysis of the Voyager 1 UVS solar occultations , 2004 .

[5]  M. Allen,et al.  Metastable Diacetylene Reactions as Routes to Large Hydrocarbons in Titan's Atmosphere , 1996 .

[6]  Kei Sato,et al.  Measurements of Thermal Rate Constants for the Reactions of N(2D,2P) with C2H4 and C2D4 between 225 and 292 K , 1999 .

[7]  Michael J Pilling,et al.  H atom yields from the reactions of CN radicals with C2H2, C2H4, C3H6, trans-2-C4H8, and iso-C4H8. , 2007, The journal of physical chemistry. A.

[8]  David R. Lide,et al.  CRC HANDBOOK of THERMOPHYSICAL and THERMOCHEMICAL DATA , 1994 .

[9]  L. Stief,et al.  Kinetics of the Reaction of Atomic Hydrogen with Cyanoacetylene from T = 200 to 298 K , 2004 .

[10]  Ian W. M. Smith,et al.  Rate constants for the reactions of CN with hydrocarbons at low and ultra-low temperatures , 1993 .

[11]  P. Dagdigian,et al.  The electronic spectrum of methyleneimine , 2004 .

[12]  W. A. Payne,et al.  THE REACTION BETWEEN N(4S) AND C2H3 : RATE CONSTANT AND PRIMARY REACTION CHANNELS , 1996 .

[13]  Athena Coustenis,et al.  Coupling photochemistry with haze formation in Titan's atmosphere, Part I: Model description , 2008 .

[14]  P. Irwin,et al.  Condensation in Titan's stratosphere during polar winter , 2008 .

[15]  R. West,et al.  The Cassini UVIS Stellar Probe of the Titan Atmosphere , 2005, Science.

[16]  B. Minaev,et al.  Dissociative Recombination of HCNH+: Absolute Cross-Sections and Branching Ratios , 2001 .

[17]  V. Anicich.  An index of the literature for bimolecular gas phase cation-molecule reaction kinetics , 2003 .

[18]  W. Green,et al.  Pressure and temperature dependence of the reaction of vinyl radical with ethylene. , 2007, The journal of physical chemistry. A.

[19]  R. Kaiser,et al.  An ab initio study on the formation of interstellar tricarbon isomers l-C3(X1Σg+) and c-C3(X3A2′) , 2002 .

[20]  R. Lorenz,et al.  A model of variability in Titan's atmospheric structure , 2013 .

[21]  A. Coustenis,et al.  Coupling photochemistry with haze formation in Titan's atmosphere, Part II: Results and validation with Cassini/Huygens data , 2008 .

[22]  D. Talbi,et al.  Isomerization versus hydrogen exchange reaction in the HNC ⇌ HCN conversion , 1996 .

[23]  Shih-Huang Lee,et al.  Exploring the dynamics of reaction N((2)D)+C2H4 with crossed molecular-beam experiments and quantum-chemical calculations. , 2011, Physical chemistry chemical physics : PCCP.

[24]  K. Honma,et al.  Vacuum ultraviolet photodissociation dynamics of acetonitrile , 1998 .

[25]  T. Takayanagi,et al.  Direct ab initio classical trajectory calculations for the N(2D)+CH4 insertion reaction , 1999 .

[26]  M. Dobrijevic,et al.  Photochemistry of C3Hp hydrocarbons in Titan’s stratosphere revisited , 2013 .

[27]  Ian W. M. Smith,et al.  The production of HCN dimer and more complex oligomers in dense interstellar clouds , 2001 .

[28]  S. Satyapal,et al.  Photodissociation of acetylene at 193.3 nm , 1991 .

[29]  A. Ravishankara,et al.  Rate coefficients for the OH + acetaldehyde (CH3CHO) reaction between 204 and 373 K , 2008 .

[30]  T. Geballe,et al.  Clouds, haze, and CH4, CH3D, HCN, and C2H2 in the atmosphere of Titan probed via 3 μm spectroscopy , 2005 .

[31]  J. Cui.  Analysis of Titan's neutral upper atmosphere from Cassini Ion Neutral Mass Spectrometer measurements in the Closed Source Neutral mode , 2009 .

[32]  R. Kaiser,et al.  Reaction dynamics of carbon-bearing radicals in circumstellar envelopes of carbon stars. , 2006, Faraday discussions.

[33]  M. Lin,et al.  CN radical reactions with hydrogen cyanide and cyanogen - Comparison of theory and experiment , 1992 .

[34]  S. Atreya,et al.  Current state of modeling the photochemistry of Titan's mutually dependent atmosphere and ionosphere , 2004 .

[35]  Yi‐hong Ding,et al.  Cyanomethylidyne: a reactive carbyne radical. , 2006, Chemphyschem : a European journal of chemical physics and physical chemistry.

[36]  H. Baumgärtel,et al.  VUV photophysics of acetic acid: Fragmentation, fluorescence and ionization in the 6–23 eV region , 2006 .

[37]  Yuk L. Yung,et al.  Photolytically Generated Aerosols in the Mesosphere and Thermosphere of Titan , 2007, 0705.0145.

[38]  Zhiqiang Zhu,et al.  Kinetics of CCN Radical Reactions with a Series of Normal Alkanes , 2003 .

[39]  S. Leone,et al.  Kinetics of C2H reactions with hydrocarbons and nitriles in the 104-296 K temperature range , 2004 .

[40]  James A. Miller,et al.  The H + C2H2(+M) ⇄ C2H3(+M) and H + C2H2(+M) ⇄ C2H5(+M) reactions: Electronic structure, variational transition-state theory, and solutions to a two-dimensional master equation , 2004 .

[41]  Kaori Fukuzawa,et al.  Molecular Orbital Study of Neutral-Neutral Reactions concerning HC3N Formation in Interstellar Space , 1997 .

[42]  V. Krasnopolsky.  Titan's photochemical model: Further update, oxygen species, and comparison with Triton and Pluto , 2012 .

[43]  B. Funke,et al.  Distribution of HCN in Titan's upper atmosphere from Cassini/VIMS observations at 3 μm , 2011 .

[44]  D. A. Orlov,et al.  COLD ELECTRON REACTIONS PRODUCING THE ENERGETIC ISOMER OF HYDROGEN CYANIDE IN INTERSTELLAR CLOUDS , 2012 .

[45]  P. J. Schinder,et al.  Titan's Atmospheric Temperatures, Winds, and Composition , 2005, Science.

[46]  A. Laufer,et al.  The 1,1-elimination of hydrogen cyanide and formation of triplet vinylidene from the photolysis of acrylonitrile , 1992 .

[47]  Michael J. Berry,et al.  CN photodissociation and predissociation chemical lasers: Molecular electronic and vibrational laser emissions , 1974 .

[48]  C. McKay,et al.  The role of organic haze in Titan's atmospheric chemistry II. Effect of heterogeneous reaction to the hydrogen budget and chemical composition of the atmosphere , 2008 .

[49]  S. Leone,et al.  Bimolecular rate constant and product branching ratio measurements for the reaction of C2H with ethene and propene at 79 K. , 2012, The journal of physical chemistry. A.

[50]  Stanislav I. Stoliarov,et al.  Kinetics of the C2H3 + H2 ⇄ H + C2H4 and CH3 + H2 ⇄ H + CH4 Reactions , 1996 .

[51]  J. Wahlund,et al.  Negative ion chemistry in Titan's upper atmosphere , 2008 .

[52]  Michel Dobrijevic,et al.  Photochemical kinetics uncertainties in modeling Titan's atmosphere: First consequences , 2007 .

[53]  W. Boullart,et al.  Product distributions of the acetylene + atomic oxygen and HCCO (ketenyl) + atomic hydrogen reactions. Rate constant of methylene(.apprx.X3B1) + atomic hydrogen , 1992 .

[54]  B. Bézard,et al.  Oxygen compounds in Titan's stratosphere as observed by Cassini CIRS , 2007 .

[55]  M. Nguyen,et al.  A Theoretical Study of the CH2N System: Reactions in both Lowest Lying Doublet and Quartet States , 1998 .

[56]  An experimental study of the reaction kinetics of C2(X1Σg+) with hydrocarbons (CH4, C2H2, C2H4, C2H6 and C3H8) over the temperature range 24–300 K: Implications for the atmospheres of Titan and the Giant Planets , 2007 .

[57]  D. W. Clarke,et al.  Photodissociation of cyanoacetylene: application to the atmospheric chemistry of Titan. , 1995, Icarus.

[58]  C. McKay,et al.  The role of organic haze in Titan's atmospheric chemistry: I. Laboratory investigation on heterogeneous reaction of atomic hydrogen with Titan tholin , 2008 .

[59]  H. Okabe,et al.  Photochemistry of acetylene at 193.3 nm , 1993 .

[60]  N. Mason,et al.  Electronic excitation and optical cross sections of methylamine and ethylamine in the UV–VUV spectral region , 2002 .

[61]  R. Khanna,et al.  Condensed species in Titan's atmosphere: Identification of crystalline propionitrile (C2H5CN, CH3CH2CN) based on laboratory infrared data , 2005 .

[62]  Y. Osamura,et al.  NCCN and NCCCCN formation in titan's atmosphere: 2. HNC as a viable precursor , 2004 .

[63]  David S. Green,et al.  Time‐resolved vibrational chemiluminescence: Rate constants for the reactions of F atoms with H2O and HCN, and for the relaxation of HF (v = 1) by H2O and HCN , 1986 .

[64]  M. Lin,et al.  Kinetics of CN(X 2Σ+) radical reactions with HCN, BrCN and CH3CN , 1989 .

[65]  K. Kanda,et al.  Photodissociation of some simple nitriles in the extreme vacuum ultraviolet region , 1999 .

[66]  T. H. Dunning.  Gaussian basis sets for use in correlated molecular calculations. I. The atoms boron through neon and hydrogen , 1989 .

[67]  M. Pilling,et al.  Experimental and master equation study of the kinetics of OH + C2H2: temperature dependence of the limiting high pressure and pressure dependent rate coefficients. , 2007, The journal of physical chemistry. A.

[68]  S. Klippenstein,et al.  RAPID ASSOCIATION REACTIONS AT LOW PRESSURE: IMPACT ON THE FORMATION OF HYDROCARBONS ON TITAN , 2011 .

[69]  N. Balucani,et al.  Crossed molecular beam studies of bimolecular reactions of relevance in combustion , 2012 .

[70]  A. Coustenis,et al.  Latitudinal variations of HCN, HC3N, and C2N2 in Titan's stratosphere derived from Cassini CIRS data , 2006 .

[71]  P. Gierasch,et al.  Titan’s winter polar vortex structure revealed by chemical tracers , 2008 .

[72]  R. Turco,et al.  A physical model of Titan's aerosols. , 1992, Icarus.

[73]  P. Lavvas,et al.  Energy deposition and primary chemical products in Titan’s upper atmosphere , 2010 .

[74]  Geoffrey B. Smith,et al.  Recurring chains following addition of atomic hydrogen to acetylene , 1986 .

[75]  M. Nguyen,et al.  Another Look at the Decomposition of Methyl Azide and Methanimine: How Is HCN Formed? , 1996 .

[76]  Conor A. Nixon,et al.  Analysis of Cassini/CIRS limb spectra of Titan acquired during the nominal mission I. Hydrocarbons, nitriles and CO2 vertical mixing ratio profiles , 2010 .

[77]  A. Laufer.  Quenching of triplet vinylidene radicals by helium , 1983 .

[78]  R. M. Lee,et al.  Gas phase equilibrium between acetaldehyde and paraldehyde, thermodynamic values for the trimerisation of acetaldehyde and the polymerisability of paraldehyde , 1973 .

[79]  Nadia Balucani,et al.  CRITICAL REVIEW OF N, N+, N+2, N++, And N++2 MAIN PRODUCTION PROCESSES AND REACTIONS OF RELEVANCE TO TITAN'S ATMOSPHERE , 2013 .

[80]  K. Morokuma,et al.  Theoretical Study of Potential Energy Surface and Thermal Rate Constants for the C6H5 + H2 and C6H6 + H Reactions , 1997 .

[81]  Marzio Rosi,et al.  Formation of nitriles and imines in the atmosphere of Titan: combined crossed-beam and theoretical studies on the reaction dynamics of excited nitrogen atoms N(2D) with ethane. , 2010, Faraday discussions.

[82]  A. Coustenis,et al.  Titan's Atmosphere from Voyager Infrared Observations: IV. Latitudinal Variations of Temperature and Composition , 1995 .

[83]  S. North,et al.  The radical photodissociation channel of acrylonitrile , 1996 .

[84]  A. Gandini,et al.  The photochemistry of acrylonitrile vapour at 213.9 nm , 1978 .

[85]  S. Petrie.  Reactivity of HNC with Small Hydrocarbon Radicals , 2002 .

[86]  M A Smith,et al.  Formation of NH3 and CH2NH in Titan's upper atmosphere. , 2010, Faraday discussions.

[87]  Nadia Balucani,et al.  Observation of Nitrogen-Bearing Organic Molecules from Reactions of Nitrogen Atoms with Hydrocarbons: A Crossed Beam Study of N(2D) + Ethylene , 2000 .

[88]  D. Gell,et al.  INMS-derived composition of Titan's upper atmosphere: Analysis methods and model comparison , 2009 .

[89]  N. Teanby,et al.  Mapping Titan's HCN in the far infra-red: implications for photochemistry. , 2010, Faraday discussions.

[90]  G. Mellau,et al.  High-Temperature Infrared Emission Measurements on HNC. , 2001, Journal of molecular spectroscopy.

[91]  J. Bowman,et al.  Radiative Relaxation and Isomeric Branching of Highly Excited H/C/N: The Importance of Delocalized Vibrational States , 2003 .

[92]  S. Vázquez,et al.  Ab initio and RRKM study of the HCN/HNC elimination channels from vinyl cyanide. , 2011, The journal of physical chemistry. A.

[93]  F. Hourdin,et al.  Titan's stratospheric composition driven by condensation and dynamics , 2004 .

[94]  Aron Kuppermann,et al.  Singlet→triplet transitions in C≡N containing molecules by electron impact , 1984 .

[95]  J. Mittal,et al.  Absolute primary H atom quantum yield measurements in the 193.3 and 121.6 nm photodissociation of acetylene , 2002 .

[96]  Xuri Huang,et al.  A Barrier-Free Atomic Radical-Molecule Reaction:  F + Propene. , 2006, Journal of chemical theory and computation.

[97]  P. Hartogh,et al.  The abundance, vertical distribution and origin of H2O in Titan's atmosphere: Herschel observations and photochemical modelling , 2012 .

[98]  D. A. Horner,et al.  A theoretical study of the energetics of insertion of dicarbon (C2) and vinylidene into methane CH bonds , 1995 .

[99]  M. Frenklach,et al.  Calculations of rate coefficients for the chemically activated reactions of acetylene with vinylic and aromatic radicals , 1994 .

[100]  Bryan M. Wong,et al.  A new approach toward transition state spectroscopy. , 2013, Faraday discussions.

[101]  H. Wagner,et al.  A direct study of the reactions of methylene(~X 3B1) radicals with hydrogen and deuterium atoms , 1987 .

[102]  H. Wagner,et al.  Elementary reactions of NH(a1Δ) and NH(X3Σ) with N, O and NO , 1994 .

[103]  R. Lucchese,et al.  Photolysis of methane revisited at 121.6 nm and at 118.2 nm: quantum yields of the primary products, measured by mass spectrometry. , 2011, Physical chemistry chemical physics : PCCP.

[104]  P. Pernot,et al.  Epistemic bimodality and kinetic hypersensitivity in photochemical models of Titan's atmosphere , 2008 .

[105]  B. Bézard,et al.  The Titan 14N/15N and 12C/13C isotopic ratios in HCN from Cassini/CIRS , 2007 .

[106]  S. Klippenstein,et al.  Low temperature rate coefficients for the reaction CN + HC3N. , 2013, The journal of physical chemistry. A.

[107]  A. Coustenis,et al.  DETECTION OF PROPENE IN TITAN'S STRATOSPHERE , 2013, 1309.4489.

[108]  G. Nyman,et al.  Adiabatic capture theory applied to N+NH-->N2+H at low temperature. , 2007, The journal of physical chemistry. A.

[109]  Emmanuel Lellouch,et al.  Erratum: ``Vertical distribution of Titan's atmospheric neutral constituents'' , 1996 .

[110]  A. Canosa,et al.  Rate coefficients for the reactions of C2(a(3)Pi(u)) and C2(X(1)Sigma(g)(+)) with various hydrocarbons (CH4, C2H2, C2H4, C2H6, and C3H8): a gas-phase experimental study over the temperature range 24-300 K. , 2008, The journal of physical chemistry. A.

[111]  Toshiyuki Takayanagi,et al.  Measurements of Thermal Rate Constants and Theoretical Calculations for the N(2D,2P) + C2H2and C2D2Reactions , 1998 .

[112]  P. Hartogh,et al.  Constraints on Titan's middle atmosphere ammonia abundance from Herschel/SPIRE sub-millimetre spectra $ , 2013 .

[113]  John T. Herron,et al.  Evaluated Chemical Kinetics Data for Reactions of N(2D), N(2P), and N2(A 3Σu+) in the Gas Phase , 1999 .

[114]  P. Pernot,et al.  Production of neutral species in Titan's ionosphere through dissociative recombination of ions as measured by INMS , 2011 .

[115]  Kei Sato,et al.  KINETIC STUDIES ON THE N(2D, 2P) + CH4 AND CD4 REACTIONS : THE ROLE OF NONADIABATIC TRANSITIONS ON THERMAL RATE CONSTANTS , 1999 .

[116]  V. L. Orkin,et al.  Chemical Kinetics and Photochemical Data for Use in Atmospheric Studies: Evaluation Number 18 , 2015 .

[117]  N. Nakashima,et al.  Photochemistry of acetylene at 193 nm: Two pathways for diacetylene formation , 1986 .

[118]  Christopher J. Mertens,et al.  Ionization processes in the atmosphere of Titan - III. Ionization by high-Z nuclei cosmic rays , 2011 .

[119]  T. Geballe,et al.  High-Resolution 3 Micron Spectroscopy of Molecules in the Mesosphere and Troposphere of Titan , 2003 .

[120]  E. Lellouch,et al.  Photochemistry and diffusion in Jupiter's stratosphere: Constraints from ISO observations and comparisons with other giant planets , 2005 .

[121]  J. Tomeczek,et al.  The role of N2O and NNH in the formation of NO via HCN in hydrocarbon flames , 2003 .

[122]  S. Leone,et al.  Direct measurements of rate coefficients for the reaction of ethynyl radical (C2H) with C2H2 at 90 and 120 K using a pulsed Laval nozzle apparatus , 2000 .

[123]  M. Dobrijevic,et al.  Coupling of oxygen, nitrogen, and hydrocarbon species in the photochemistry of Titan’s atmosphere , 2014 .

[124]  T. Carrington,et al.  Photodissociation of HCN at 157 nm: Energy disposal in the CN(A 2Π) fragment , 2000 .

[125]  P. Monks,et al.  The kinetics of the formation of nitrile compounds in the atmospheres of Titan and Neptune , 1993 .

[126]  F. Hourdin,et al.  Diagnostics of Titan’s stratospheric dynamics using Cassini/CIRS data and the 2-dimensional IPSL circulation model , 2008 .

[127]  S. Hoffmann,et al.  High resolution photo-absorption studies of acrylonitrile, C2H3CN, and acetonitrile, CH3CN , 2003 .

[128]  Michel Dobrijevic,et al.  Neutral production of hydrogen isocyanide (HNC) and hydrogen cyanide (HCN) in Titan's upper atmosphere , 2012 .

[129]  D. G. Keil,et al.  An investigation of nonequilibrium kinetic isotope effects in chemically activated vinyl radicals , 1976 .

[130]  D. Edvardsson,et al.  A photoabsorption, photodissociation and photoelectron spectroscopy study of NH3 and ND3 , 1999 .

[131]  P. Hartogh,et al.  First results of Herschel-SPIRE observations of Titan , 2011 .

[132]  R. West,et al.  The mesosphere and lower thermosphere of Titan revealed by Cassini/UVIS stellar occultations , 2011 .

[133]  Roger V. Yelle,et al.  Ion chemistry and N-containing molecules in Titan's upper atmosphere , 2007 .

[134]  Y. Osamura,et al.  NCCN and NCCCCN Formation in Titan's Atmosphere: 1. Competing Reactions of Precursor HCCN (3A‘ ‘) with H (2S) and CH3 (2A‘) , 2004 .

[135]  Nicolas Fray,et al.  Sublimation of ices of astrophysical interest: A bibliographic review , 2009 .

[136]  A. Coustenis,et al.  Titan's atmosphere from voyager infrared observations: III. Vertical distributions of hydrocarbons and nitriles near Titan's North Pole , 1991 .

[137]  P. Hartogh,et al.  First detection of hydrogen isocyanide (HNC) in Titan's atmosphere , 2011 .

[138]  R. Kaiser,et al.  Potential Energy Surface and Product Branching Ratios for the Reaction of Dicarbon, C2(X1Σg+), with Methylacetylene, CH3CCH(X1A1): An Ab Initio/RRKM Study , 2006 .

[139]  S. North,et al.  The unimolecular dissociation of vinylcyanide: A theoretical investigation of a complex multichannel reaction , 1999 .

[140]  Conor A. Nixon,et al.  Vertical profiles of HCN, HC3N, and C2H2 in Titan's atmosphere derived from Cassini/CIRS data , 2007 .

[141]  W. A. Payne,et al.  Absolute rate constant for the reaction of atomic hydrogen with acetylene over an extended pressure and temperature range , 1976 .

[142]  P. Pernot,et al.  How measurements of rate coefficients at low temperature increase the predictivity of photochemical models of Titan's atmosphere. , 2009, The journal of physical chemistry. A.

[143]  Pascal Rannou,et al.  Titan atmosphere database , 2005 .

[144]  Kensei Kobayashi,et al.  DFT study of HCN and N≡C-C≡N reactions with hydrogen species , 2004 .

[145]  A. Marten,et al.  New Millimeter Heterodyne Observations of Titan: Vertical Distributions of Nitriles HCN, HC3N, CH3CN, and the Isotopic Ratio 15N/14N in Its Atmosphere , 2002 .

[146]  H. Schlegel,et al.  Ab initio classical trajectory study of the dissociation of neutral and positively charged methanimine (CH2NHn+ n = 0-2). , 2009, The journal of physical chemistry. A.

[147]  Frédéric Hourdin,et al.  Seasonal Variations of Titan's Atmospheric Composition , 2001 .

[148]  H. Okabe.  Photochemistry of acetylene at 1849 Å , 1983 .

[149]  Niann S. Wang,et al.  Temperature dependence of cyanogen radical reactions with selected alkanes: CN reactivities towards primary, secondary and tertiary CH bonds , 1992 .

[150]  E. Lellouch,et al.  Water vapor in Titan's stratosphere from Cassini CIRS far-infrared spectra , 2012 .

[151]  S. Klippenstein,et al.  Long-range transition state theory. , 2005, The Journal of chemical physics.

[152]  C. Griffith,et al.  HCN fluorescence on Titan , 2003 .

[153]  P. Caridade,et al.  Unimolecular and bimolecular calculations for HN2. , 2005, The journal of physical chemistry. A.

[154]  E. Barth,et al.  Microphysical modeling of ethane ice clouds in titan's atmosphere , 2003 .

[155]  R. Mataloni,et al.  Vacuum‐Ultraviolet Photolysis of Acetylene , 1965 .

[156]  K. S. Shin,et al.  Rate constants (296-1700 K) for the reactions ethynyl radical + acetylene .fwdarw. C4H2 + H and C2D + C2D2 .fwdarw. C4D2 + D , 1991 .

[157]  L. C. Lee.  CN(A 2Πi→X 2Σ+) and CN(B 2Σ+→X 2Σ+) yields from HCN photodissociation , 1980 .

[158]  I. Smith,et al.  Rate constants and branching ratios for the reaction of CH radicals with NH3: a combined experimental and theoretical study. , 2012, The journal of physical chemistry. A.

[159]  J. S. Francisco,et al.  Computational study of the linear proton bound ion-molecule complexes of HCNH+ with HCN and HNC. , 2013, The Journal of chemical physics.

[160]  B. Bézard,et al.  Titan’s stratospheric C2N2, C3H4, and C4H2 abundances from Cassini/CIRS far-infrared spectra , 2009 .

[161]  R. Samuelson,et al.  C4N2 ice in Titan's north polar stratosphere , 1997 .

[162]  J. Halpern,et al.  The UV photochemistry of cyanoacetylene , 1988 .

[163]  Zesheng Li,et al.  A Theoretical Study of the Photodissociation Mechanism of Cyanoacetylene in Its Lowest Singlet and Triplet Excited States , 2008 .

[164]  D. Truhlar,et al.  Exploring the Limit of Accuracy of the Global Hybrid Meta Density Functional for Main-Group Thermochemistry, Kinetics, and Noncovalent Interactions. , 2008, Journal of chemical theory and computation.

[165]  S. Klippenstein,et al.  Predictive theory for the combination kinetics of two alkyl radicals. , 2006, Physical chemistry chemical physics : PCCP.

[166]  M. Khlifi,et al.  GAS INFRARED SPECTRA, ASSIGNMENTS, AND ABSOLUTE IR BAND INTENSITIES OF C4N2 IN THE 250-3500 CM-1 REGION: IMPLICATIONS FOR TITAN'S STRATOSPHERE , 1997 .

[167]  T. Takayanagi,et al.  Theoretical study on HNC(1Σ) production from the C2(X1Σg+)+NH(X3Σ-) reaction , 2006 .

[168]  Y. Lee,et al.  Photodissociation of acrylonitrile at 193 nm: A photofragment translational spectroscopy study using synchrotron radiation for product photoionization , 1998 .

[169]  Marzio Rosi,et al.  Combined crossed molecular beam and theoretical studies of the N(2D) + CH4 reaction and implications for atmospheric models of Titan. , 2009, The journal of physical chemistry. A.

[170]  E. Lellouch,et al.  The vertical Distribution and Origin of HCN in Neptune's Atmosphere , 1994 .

[171]  J. Troe,et al.  A KINETIC DATABASE FOR ASTROCHEMISTRY (KIDA) , 2012, 1201.5887.

[172]  Roger Atkinson,et al.  Evaluated kinetic and photochemical data for atmospheric chemistry: Volume I - gas phase reaxtions of Ox, HOx, NOx and SOx species , 2004 .

[173]  H. Hippler,et al.  The temperature and pressure dependence of the reaction CH+H2⇔CH3⇔CH2+H , 1997 .

[174]  S. Leone,et al.  Rate coefficients for reactions of ethynyl radical (C2H) with HCN and CH3CN: Implications for the formation of complex nitriles on Titan , 1997 .

[175]  K. Hickson,et al.  Reaction kinetics to low temperatures. Dicarbon + acetylene, methylacetylene, allene and propene from 77 < or = T < or = 296 K. , 2008, Physical chemistry chemical physics : PCCP.

[176]  Raymond W. Walker,et al.  Evaluated kinetic data for combustion modelling supplement I , 1994 .

[177]  V. Krasnopolsky.  A photochemical model of Titan's atmosphere and ionosphere , 2009 .

[178]  E. Steacie,et al.  THE PHOTOLYSIS OF METHYL CYANIDE AT 1849 Å , 1958 .

[179]  R. Yelle,et al.  Origin of oxygen species in Titan's atmosphere , 2008 .

[180]  C. Mertens,et al.  Computing uncertainties in ionosphere‐airglow models: I. Electron flux and species production uncertainties for Mars , 2012 .

[181]  H. Dai,et al.  Photodissociation of vinyl cyanide at 193 nm: Nascent product distributions of the molecular elimination channels. , 2009, The Journal of chemical physics.

[182]  P. Redondo,et al.  Theoretical survey of the NH+CH3 potential energy surface in relation to Titan atmospheric chemistry , 2006 .

[183]  Michel Dobrijevic,et al.  Photochemical kinetics uncertainties in modeling Titan’s atmosphere: A review , 2006 .

[184]  Xuri Huang,et al.  F/Cl + C2H2 reactions: Are the addition and hydrogen abstraction direct processes? , 2006 .

[185]  D. Golden.  The reaction OH + C2H4: an example of rotational channel switching. , 2012, The journal of physical chemistry. A.

[186]  Roger V. Yelle,et al.  The Nitrogen Chemistry of Titan’s Upper Atmosphere Revealed , 2006 .