Temperature dependence of HC3N, C6H2, and C4N2 mid-UV absorption coefficients. Application to the interpretation of Titan's atmospheric spectra

Bénilan, Y.; Andrieux, Dominique; Khlifi, M.; Bruston, P.; Raulin, F.; Guillemin, Jean‐Claude; Cossart‐Magos, Claudina

doi:10.1007/bf00644323

Cited by 16 publications

(8 citation statements)

References 18 publications

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“…As illustrated in Fig. 2 (top), the ultraviolet absorption spectrum of C 4 N 2 ice at 100 K has structure at o300 nm in agreement with the gas-phase spectrum [36][37][38][39] , but also a featureless long-wavelength absorption stretching to 4360 nm, beyond where the gas-phase absorption ends. The broad continuum absorption at longer wavelengths than B350 nm could be due to the weak singlet-triplet absorption amplified in the condensed phase, in agreement with detection of phosphorescence from the first triplet (T 1 ) state of C 4 N 2 at B390 nm (ref.…”

Section: Resultssupporting

confidence: 60%

Photochemical activity of Titan’s low-altitude condensed haze

et al. 2013

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Titan, the largest moon of Saturn and similar to Earth in many aspects, has unique orangeyellow colour that comes from its atmospheric haze, whose formation and dynamics are far from well understood. Present models assume that Titan's tholin-like haze formation occurs high in atmosphere through gas-phase chemical reactions initiated by high-energy solar radiation. Here we address an important question: Is the lower atmosphere of Titan photochemically active or inert? We demonstrate that indeed tholin-like haze formation could occur on condensed aerosols throughout the atmospheric column of Titan. Detected in Titan's atmosphere, dicyanoacetylene (C 4 N 2 ) is used in our laboratory simulations as a model system for other larger unsaturated condensing compounds. We show that C 4 N 2 ices undergo condensed-phase photopolymerization (tholin formation) at wavelengths as long as 355 nm pertinent to solar radiation reaching a large portion of Titan's atmosphere, almost close to the surface.

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Section: Resultssupporting

confidence: 60%

Photochemical activity of Titan’s low-altitude condensed haze

et al. 2013

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“…1) is a rod-shaped molecule, first synthesized by Moureu and Bongrand [1]. Its IR and Raman vibrational spectroscopy was thoroughly studied [2][3][4][5], as were the mid-UV [6,7] and vacuum-UV [8] electronic transitions. Electronic luminescence (phosphorescence) has so far been found for several cyanoacetylene-family molecules dispersed in solid rare-gas matrices, namely for NC 4 N [9] and HC 5 N (cyanodiacetylene) [10], for another isoelectronic pair: NC 2 N (cyanogen) [11] and C 3 N -(cyanoacetylide anion) [12], and finally for NC 6 N [13].…”

Section: Introductionmentioning

confidence: 99%

Low-temperature phosphorescence of dicyanoacetylene in rare gas solids

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et al. 2012

Low Temperature Physics

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“…Rennie et al [1998];Pantos et al [1978] Yokoyama et al [1990;Connors et al [1974];Bénilan et al [1996] at 233 K…”

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confidence: 99%

Current state of modeling the photochemistry of Titan's mutually dependent atmosphere and ionosphere

2004

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[1] In the context of recent observations, microphysical models, and laboratory data, a photochemical model of Titan's atmosphere, including updated chemistry focusing on rate coefficients and cross sections measured under appropriate conditions, has been developed to increase understanding of these processes and improve upon previous Titan photochemical models. The model employs a two-stream discrete ordinates method to characterize the transfer of solar radiation, and the effects of electron-impact, cosmic-ray deposition, and aerosol opacities from fractal and Mie particles are analyzed. Sensitivity studies demonstrate that an eddy diffusion profile with a homopause level of 850 km and a methane stratospheric mole fraction of 2.2% provides the best fit of stratospheric and upper atmosphere observations and an improved fit over previous Titan photochemical models. Lack of fits for C 3 H 8 , HC 3 N, and possibly C 2 H 3 CN can be resolved with adjustments in aerosol opacity. The model presents a benzene profile consistent with its detection in Titan's stratosphere , which may play an important role in the formation of Titan hazes. An electron peak concentration of 4200 cm À3 is calculated, which exceeds observations by 20%, considerably lower than previous ionosphere models. With adjustments in aerosol opacities and surface fluxes the model illustrates that reasonable fits to existing observations are possible with a single eddy diffusion profile, contrary to the conclusions of previous Titan models. These results will aid in the receipt and interpretation of data from Cassini-Huygens, which will arrive at Titan in 2004 and deploy a probe into Titan's atmosphere in January 2005.

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Temperature dependence of HC3N, C6H2, and C4N2 mid-UV absorption coefficients. Application to the interpretation of Titan's atmospheric spectra

Cited by 16 publications

References 18 publications

Photochemical activity of Titan’s low-altitude condensed haze

Photochemical activity of Titan’s low-altitude condensed haze

Low-temperature phosphorescence of dicyanoacetylene in rare gas solids

Current state of modeling the photochemistry of Titan's mutually dependent atmosphere and ionosphere

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