Photochemistry of Saturn's Atmosphere I. Hydrocarbon Chemistry and Comparisons with ISO Observations

Moses, J. I.; Bézard, Bruno; Lellouch, E.; Gladstone, G. R.; Feuchtgruber, H.; Allen, Mark

doi:10.1006/icar.1999.6270

Cited by 282 publications

(346 citation statements)

References 159 publications

Supporting

Mentioning

326

Contrasting

Order By: Relevance

“…throughout the 1-1000 mbar range, as reviewed by Moses et al (2000a). The inclusion of additional gases into the basic model will be described in Sect.…”

Section: Saturn Continuum Modelling: Temperatures Ph 3 and Nhmentioning

confidence: 99%

Sub-millimetre spectroscopy of Saturn’s trace gases fromHerschel/SPIRE

Fletcher

Swinyard

Salji

et al. 2012

A&A

View full text Add to dashboard Cite

Aims. We provide an extensive new sub-millimetre survey of the trace gas composition of Saturn's atmosphere using the broad spectral range (15-51 cm −1 ) and high spectral resolution (0.048 cm −1 ) offered by Fourier transform spectroscopy by the Herschel/SPIRE instrument (Spectral and Photometric Imaging REceiver). Observations were acquired in June 2010, shortly after equinox, with negligible contribution from Saturn's ring emission. Methods. Tropospheric temperatures and the vertical distributions of phosphine and ammonia are derived using an optimal estimation retrieval algorithm to reproduce the sub-millimetre data. The abundance of methane, water and upper limits on a range of different species are estimated using a line-by-line forward model. Results. Saturn's disc-averaged temperature profile is found to be quasi-isothermal between 60 and 300 mbar, with uncertainties of 7 K due to the absolute calibration of SPIRE. Modelling of PH 3 rotational lines confirms the vertical profile derived in previous studies and shows that negligible PH 3 is present above the 10-to 20-mbar level. The upper tropospheric abundance of NH 3 appears to follow a vapour pressure distribution throughout the region of sensitivity in the SPIRE data, but the degree of saturation is highly uncertain. The tropospheric CH 4 abundance and Saturn's bulk C/H ratio are consistent with Cassini studies. We improve the upper limits on several species (H 2 S, HCN, HCP and HI); provide the first observational constraints on others (SO 2 , CS, methanol, formaldehyde, CH 3 Cl); and confirm previous upper limits on HF, HCl and HBr. Stratospheric emission from H 2 O is suggested at 36.6 and 38.8 cm −1 with a 1σ significance level, and these lines are used to derive mole fractions and column abundances consistent with ISO and SWAS estimations a decade earlier.

show abstract

“…throughout the 1-1000 mbar range, as reviewed by Moses et al (2000a). The inclusion of additional gases into the basic model will be described in Sect.…”

Section: Saturn Continuum Modelling: Temperatures Ph 3 and Nhmentioning

confidence: 99%

Sub-millimetre spectroscopy of Saturn’s trace gases fromHerschel/SPIRE

Fletcher

Swinyard

Salji

et al. 2012

A&A

View full text Add to dashboard Cite

show abstract

“…It has been also detected on Jupiter and Saturn in nonauroral regions (Bézard et al 2001). The analysis of the mass and distributions of C 2 H 4 on the Jupiter-orbiting comet SL9 was presented in Griffith et al (1997), and the investigation of the photochemistry on some hydrocarbons from the Infrared Space Observatory (ISO) observations was reported by Moses et al (2000). Again in Saturn, ethylene has recently been detected in the hot temperature beacon (Hesman et al 2012) region using the Composite Infrared Spectrometer (CIRS) with strong thermal emission at 10.5 µm.…”

Section: Introductionmentioning

confidence: 99%

First theoretical global line lists of ethylene (¹²C₂H₄) spectra for the temperature range 50−700 K in the far-infrared for quantification of absorption and emission in planetary atmospheres

Rey

Delahaye

Nikitin

et al. 2016

A&A

View full text Add to dashboard Cite

We present the construction of complete and comprehensive ethylene line lists for the temperatures 50−700 K based on accurate ab initio potential and dipole moment surfaces and extensive first-principle calculations. Three lists spanning the [0−6400] cm −1 infrared region were built at T = 80, 160, and 296 K, and two lists in the range [0−5200] cm −1 were built at 500 and 700 K. For each of these five temperatures, we considered possible convergence problems to ensure reliable opacity calculations. Our final list at 700 K was computed up to J = 71 and contains almost 60 million lines for intensities I > 5 × 10 −27 cm/molecule. Comparisons with experimental spectra carried out in this study showed that for the most active infrared bands, the accuracy of band centers in our theoretical lists is better on average than 0.3 cm −1 , and the integrated absorbance errors in the intervals relevant for spectral analyses are about 1−3%. These lists can be applied to simulations of absorption and emission spectra, radiative and non-LTE processes, and opacity calculations for planetary and astrophysical applications.

show abstract

“…A new age began with the implementation of successive additive reactions involving acetylene with n−C 4 H 3 or n−C 4 H 5 , and the recombination A&A 532, A40 (2011) of the propargyl radical C 3 H 3 , which were simultaneously included in a photochemical model of Saturn's atmosphere (Moses et al 2000), which led then to the formation of the first aromatic compound. On further reaction with C 2 H 2 , this aromatic produces higher hydrocarbons including multi-ring species starting from naphthalene to pyrene.…”

Section: Introductionmentioning

confidence: 99%

Insights into the role of polycyclic aromatic hydrocarbon condensation in haze formation in Jupiter’s atmosphere

Biennier

Sabbah

Chandrasekaran

et al. 2011

A&A

View full text Add to dashboard Cite

Context. The haze in the atmosphere of Jupiter has been proposed to originate mostly from the condensation of low mass PAHs. Under this hypothesis, the transition of gas phase molecular species to solid particles is achieved by the formation of a critical nucleus composed of two small PAH molecules held together by van der Waals forces. Aims. Laboratory experiments coupled with theoretical calculations explore the thermodynamics and kinetics of PAH dimerization with the objective to assess this pathway in the production of nuclei of haze particles. Methods. We have performed experiments to identify the temperature range over which small PAH clusters form in supersaturated uniform supersonic flows. The kinetics of this formation has also been investigated. The chemical species present in the reactor are probed by a time-of-flight mass spectrometer equipped with a VUV laser for photoionisation of the neutral reagents and products. The experimental data were combined with theoretical calculations that employ careful consideration of the intermolecular interaction energies and intermolecular dynamics to estimate the binding energy, equilibrium constant, and rate constant. Results. We found that low-mass PAHs such as anthracene (C 14 H 10 ) and pyrene (C 16 H 10 ) can not homogeneously nucleate in the upper stratosphere at the altitude at which haze formation has been proposed to commence. Other chemical or physical processes should be considered to account for aerosol nuclei formation.

show abstract

Photochemistry of Saturn's Atmosphere I. Hydrocarbon Chemistry and Comparisons with ISO Observations

Cited by 282 publications

References 159 publications

Sub-millimetre spectroscopy of Saturn’s trace gases fromHerschel/SPIRE

Sub-millimetre spectroscopy of Saturn’s trace gases fromHerschel/SPIRE

First theoretical global line lists of ethylene (¹²C₂H₄) spectra for the temperature range 50−700 K in the far-infrared for quantification of absorption and emission in planetary atmospheres

Insights into the role of polycyclic aromatic hydrocarbon condensation in haze formation in Jupiter’s atmosphere

Contact Info

Product

Resources

About

Photochemistry of Saturn's Atmosphere I. Hydrocarbon Chemistry and Comparisons with ISO Observations

Cited by 282 publications

References 159 publications

Sub-millimetre spectroscopy of Saturn’s trace gases fromHerschel/SPIRE

Sub-millimetre spectroscopy of Saturn’s trace gases fromHerschel/SPIRE

First theoretical global line lists of ethylene (12C2H4) spectra for the temperature range 50−700 K in the far-infrared for quantification of absorption and emission in planetary atmospheres

Insights into the role of polycyclic aromatic hydrocarbon condensation in haze formation in Jupiter’s atmosphere

Contact Info

Product

Resources

About

First theoretical global line lists of ethylene (¹²C₂H₄) spectra for the temperature range 50−700 K in the far-infrared for quantification of absorption and emission in planetary atmospheres