The role of photochemistry in Titan’s atmospheric chemistry

Ferris, James P.; Tran, Buu N.; Joseph, Jeffrey C.; Vuitton, V.; Briggs, Robert G.; Force, Michael

doi:10.1016/j.asr.2005.03.056

Cited by 21 publications

(17 citation statements)

References 30 publications

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“…Vacuum ultraviolet (VUV) light is one of the main energetic sources driving chemical evolution occurring in planetary atmospheres and in the interstellar medium (ISM; Weber & Greenberg 1985;Ehrenfreund et al 1997;Gazeau et al 2007;Muñoz Caro & Schutte 2003;Ferris et al 2005;Tran et al 2008). Laboratory simulations of most astrophysical environments require representative VUV sources, particularly in terms of wavelength dependence and spectral irradiance.…”

Section: Introductionmentioning

confidence: 99%

Optimization of a Solar Simulator for Planetary-Photochemical Studies

Es-sebbar

Bénilan

Fray

et al. 2015

ApJS

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Low-temperature microwave-powered plasma based on hydrogen and hydrogen with noble gas mixtures are widely used as a continuous vacuum ultraviolet (VUV) source in laboratory experiments carried out to mimic the photochemistry in astrophysical environments. In this work, we present a study dedicated to optimizing such sources in terms of mono-chromaticity at Lyα (H(Lyα) line at 121.6 nm ∼ 10.2 eV) and high spectral irradiance. We report the influence on the emission spectrum of a wide range of experimental conditions including gas composition (pure H 2 , pure He, and H 2 /He mixture), gas pressure, flow rates, and microwave power. The absolute spectral irradiance delivered by this VUV light source has been measured. With a microwave input power of 100 W, the best conditions for producing a quasi-monochromatic source are a 1% H 2 /He gas mixture at a total pressure of 5 mbar and a flow rate of 2 sccm. By changing the microwave input power from 30 to 120 W, H(Lyα) increases by more than one order of magnitude. A comparison between the current measurements and the solar VUV spectral irradiance is reported over 115-170 nm.

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Section: Introductionmentioning

confidence: 99%

Optimization of a Solar Simulator for Planetary-Photochemical Studies

Es-sebbar

Bénilan

Fray

et al. 2015

ApJS

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“…These are capable not only of initiating chemistry involving neutral species but also of inducing ionization processes. 17 The photochemistry of cyanoacetylene is not only of considerable interest in the context of the atmosphere of Titan [18][19][20] but also in aspects of origin of life studies where it is often considered as a key molecule or cation in formation processes of biological molecules. 21 Laboratory studies of the photochemistry of cyanoacetylene have led to considerable understanding of the principal photodissociation processes.…”

Section: Introductionmentioning

confidence: 99%

“…21 Laboratory studies of the photochemistry of cyanoacetylene have led to considerable understanding of the principal photodissociation processes. [19][20][21][22][23][24][25][26] It is in these contexts that we consider it of interest to investigate the photophysics and photochemistry of cyanoacetylene in the VUV.…”

Section: Introductionmentioning

confidence: 99%

Ionization photophysics and spectroscopy of cyanoacetylene

Leach

Schwell

Garcı́a

et al. 2014

The Journal of Chemical Physics

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Photoionization of cyanoacetylene was studied using synchrotron radiation over the non-dissociative ionization excitation range 11-15.6 eV, with photoelectron-photoion coincidence techniques. The absolute ionization cross-section and spectroscopic aspects of the parent ion were recorded. The adiabatic ionization energy of cyanoacetylene was measured as 11.573 ± 0.010 eV. A detailed analysis of photoelectron spectra of HC3N involves new aspects and new assignments of the vibrational components to excitation of the A(2)Σ(+) and B(2)Π states of the cation. Some of the structured autoionization features observed in the 11.94 to 15.5 eV region of the total ion yield (TIY) spectrum were assigned to two Rydberg series converging to the B(2)Π state of HC3N(+). A number of the measured TIY features are suggested to be vibrational components of Rydberg series converging to the C(2)Σ(+) state of HC3N(+) at ≈17.6 eV and others to valence shell transitions of cyanoacetylene in the 11.6-15 eV region. The results of quantum chemical calculations of the cation electronic state geometries, vibrational frequencies and energies, as well as of the C-H dissociation potential energy profiles of the ground and electronic excited states of the ion, are compared with experimental observations. Ionization quantum yields are evaluated and discussed and the problem of adequate calibration of photoionization cross-sections is raised.

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“…In the Department of Chemistry at the Rensselaer Polytechnic Institute (Troy, New York, USA), Tran et al (2003) and Ferris et al (2005) performed Titan's laboratory simulations using initial gas mixtures composed of N 2 /CH 4 as well as various hydrocarbons, nitriles and/or carbon monoxide (CO) (98/2/few ppm) at a total pressure of about 900 mbar and at room temperature. The aim of their work was to simulate the action of long wavelength solar UV light on Titan's atmosphere.…”

Section: The Global Simulation Experiments Of Titan's Atmospherementioning

confidence: 99%