Molecular emissions from the atmospheres of giant planets and comets: Needs for spectroscopic and collision data

Itikawa, Yukikazu; Kim, Sang Joon; Kim, Yong Ha; Minh, Y. C.

doi:10.1016/s1049-250x(01)80056-2

Cited by 3 publications

(2 citation statements)

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“… Cravens et al , 1987; Bhardwaj et al , 1990, 1996; Gan and Cravens , 1990; Gringauz and Verigin , 1991; Haberli et al , 1996; Bhardwaj , 1999], particularly in view of intensive exploration of comet Halley in March 1986 by as many as six different spacecraft and by an extensive network of ground‐ and space‐based observations. The wealth of observations now available on comets clearly indicates that an accurate knowledge of the destruction paths of water and water‐derived products and information about other collisional processes are required to understand and interpret numerous observations of comets [e.g., Festou et al , 1993; Itikawa et al , 2001].…”

Section: Introductionmentioning

confidence: 99%

Kinetic energy distributions and line profile measurements of dissociation products of water upon electron impact

Makarov

2004

J. Geophys. Res.

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[1] The Doppler line profiles of H Ly-a (1216 Å ) and O I (1302 Å and 1152 Å ) resulting from electron impact dissociative excitation of H 2 O have been measured with a highresolution (l/Dl = 50,000) ultraviolet spectrometer. The line profiles are used to calculate the kinetic energy distribution of the hydrogen atoms produced in dissociative excitation and ionization of H 2 O at electron impact energies 25, 35, and 100 eV. Three distinct populations of H(2p) atoms were found. The kinetic energy of hydrogen atoms is found to have contributions from a low-energy component, with a mean energy of $0.2 eV at all the three electron impact energies. In addition, a medium-energy component appears with a mean energy of $2.0 eV for 35 eV electrons, and a high-energy component, $7 eV, for 100 eV electrons. The measurement of O I (1302 Å ) and O I (1152 Å ) line profiles indicate that the kinetic energy of excited O I atoms is very small ($1 eV or less) at all electron impact energies. Most of the energy released in dissociation is found in the translational energy of the hydrogen atoms. The excitation functions of H Ly-a, O I (1302 Å ) feature of oxygen, and A(0) À X(0) molecular band of hydroxyl near 3050 Å from threshold to 600 V were also measured. The spectrum (1.0 Å FWHM) of the rotational structure of OH (A À X) from electron impact dissociation indicates a high degree of rotational excitation, which is almost identical to the rotational structure from dissociative recombination of H 2 O + . The results presented in this paper have important applications to planetary bodies, like comets, icy satellites of outer planets, Saturn's magnetosphere, and rings, all of which have H 2 O and its daughter products in large amount.

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Section: Introductionmentioning

confidence: 99%

Kinetic energy distributions and line profile measurements of dissociation products of water upon electron impact

Makarov

2004

J. Geophys. Res.

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“…Kim (1999) argued that the Swings effect did not significantly affect the fluorescence efficiency of the CO + 2 transitions and that the accuracy of their model was mostly limited by spectroscopic data (line positions and transition probabilities) available to them. Furthermore, their equilibrium model only includes vibrational-vibrational transitions, unlike the aforementioned studies in the prior paragraph and others (Itikawa et al 2001), which cover rovibrational transitions and focus heavily on the Renner-Teller effect. However, as demonstrated in the discussion above, significant work has been done to understand the spectrum of CO + 2 after their study was published, thus meriting a re-evaluation of the data.…”

Section: Co +mentioning

confidence: 99%

Knowledge Gaps in the Cometary Spectra of Oxygen-Bearing Molecular Cations

Fortenberry,

Bodewits,

Pierce

2021

Preprint

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Molecular cations are present in various astronomical environments, most notably in cometary atmospheres and tails where sunlight produces exceptionally bright near-UV to visible transitions. Such cations typically have longer-wavelength and brighter electronic emission than their corresponding neutrals. A robust understanding of their near-UV to visible properties would allow these cations to be used as tools for probing the local plasma environments or as tracers of neutral gas in cometary environments. However, full spectral models are not possible for characterization of small, oxygen containing molecular cations given the body of molecular data currently available. The five simplest such species (H 2 O + , CO + 2 , CO + , OH + , and O + 2 ) are well characterized in some spectral regions but are lacking robust reference data in others. Such knowledge gaps hinder fully quantitative models of cometary spectra, specifically, hindering accurate estimates of physical-chemical processes originating with the most common molecules in comets. Herein the existing spectral data are collected for these molecules and highlight the places where future work is needed, specifically where the lack of such data would greatly enhance the understanding of cometary evolution.

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Direct determination of state-to-state rotational energy transfer rate constants via a Raman-Raman double resonance technique: ortho-acetylene in v2=1 at 155 K

Doménech

Martínez

Ramos

et al. 2010

The Journal of Chemical Physics

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A new technique for the direct determination of state-to-state rotational energy transfer rate constants in the gas phase is presented. It is based on two sequential stimulated Raman processes: the first one prepares the sample in a single rotational state of an excited vibrational level, and the second one, using the high resolution quasi-continuous stimulated Raman-loss technique, monitors the transfer of population to other rotational states of the same vibrational level as a function of the delay between the pump and the probe stages. The technique is applied to the odd-J rotational states of v(2)=1 acetylene at 155 K. The experimental layout, data acquisition, retrieval procedures, and numerical treatment are described. The quantity and quality of the data are high enough to allow a direct determination of the state-to-state rate constant matrix from a fit of the experimental data, with the only conditions of detailed balance and of a closed number of states. The matrix obtained from this direct fit is also compared with those obtained using some common fitting and scaling laws.

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Molecular emissions from the atmospheres of giant planets and comets: Needs for spectroscopic and collision data

Cited by 3 publications

References 133 publications

Kinetic energy distributions and line profile measurements of dissociation products of water upon electron impact

Kinetic energy distributions and line profile measurements of dissociation products of water upon electron impact

Knowledge Gaps in the Cometary Spectra of Oxygen-Bearing Molecular Cations

Direct determination of state-to-state rotational energy transfer rate constants via a Raman-Raman double resonance technique: ortho-acetylene in v2=1 at 155 K

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