Dissociative Recombination of Molecular Ions

Mitchell, James B.

doi:10.1007/978-1-4684-5224-2_7

Cited by 25 publications

(41 citation statements)

References 66 publications

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“…The altitude of the electron peak is similar to that predicted by Whitten et al [1971], but they predicted a magnitude that should be well above 100 cm −3 and may approach 1000 cm −3 . These differences are due to a larger electron recombination rate coefficient (4 × 10 −6 cm 3 s −1 valid for PHs [ Mitchell , 1990] versus 1 × 10 −6 cm 3 s −1 [ Whitten et al , 1971]) and to a lower ionization rate by cosmic rays calculated in this paper.…”

Section: Resultsmentioning

confidence: 90%

Ion‐neutral chemistry model of the lower ionosphere of Mars

et al. 2002

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[1] The ion neutral chemistry of the lower Martian atmosphere is more complex than any other ionospheric region and similar, in some aspects, to the terrestrial D region. Two ionization sources operate at these altitude levels: solar radiation, which is the most important one below around 70 km, and galactic cosmic radiation. The interaction of positive ions and electrons produced by these ionization sources with the Martian atmosphere, which is abundant in species able to be charged negatively, produces a high variety of positive and negative ions. We present here a new model of the ion chemistry developed to calculate the concentration of electrons and most abundant ions in the atmosphere of Mars below 100 km. The present knowledge of Mars' atmosphere allows us to include new neutral and ionic species, such as nitrogen derivated, in a more detailed ion-chemistry calculation than previous lower ionopheric models of Mars. We obtain that the electron density profile has a low-altitude secondary peak below the main photon-induced maximum. This peak is placed at around 35 km and is due to the high efficiency of the electron attachment to O x molecules, which entails that the concentration of negative ions is higher than that of electrons below around 30 km. The most abundant ionic species predicted are positive ions like hydronimum hydrates H 3 O + (H 2 O) n and O 2 + and negative ions like CO 3 À (H 2 O) n and NO 3 À (H 2 O) n .

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Section: Resultsmentioning

confidence: 90%

Ion‐neutral chemistry model of the lower ionosphere of Mars

et al. 2002

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“…The majority of the measured dissociative recombination coefficients for small covalently bonded molecular ions are on the order of 10 −7 cm 3 s −1 , including that for H + 3 (Sundström et al 1994), which was previously believed to be quite small (e.g., Mitchell 1990). Recent experimental measurements have also shown that recombination coefficients from a series of alkanes, alkenes, and alkynes do not increase with size for ions with more than three carbon atoms (Lehfaoui et al 1997, RebrionRowe et al 1998).…”

Section: The Modelmentioning

confidence: 98%

Meteoric Ions in the Ionosphere of Jupiter

Kim

Pesnell

Grebowsky

et al. 2001

Icarus

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“…The rate coefficient, which was believed for a time to be quite small, 10 -s cm 3 s -1 or less, for H3 + in the ground vibrational state (see the review by Mitchell [1990]}, has been measured by several groups and more recently found to be of the order of 10-7 cm 3 s-1. We adopt here the value 1.15 x 10-7(300/T) ø'•5 cm3s -1 reported by Sundstrb'm ½t al.…”

Section: Forty Ion Recombination Reactions Have Been Includedmentioning

confidence: 99%

Chemistry of the Jovian auroral ionosphere

Perry¹,

Kim²,

Fox³

et al. 1999

J. Geophys. Res.

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Abstract. We have investigated the chemistry of the Jovian auroral thermosphere-/ionosphere by modeling the precipitation of high-energy electrons into the auroral zones using a multistream electron-transport code and three model thermospheres' a standard model based on pressure and temperature data from Galileo, and two additional models that are characterized by enhanced eddy diffusion coefficients. We have predicted the effects of precipitation of monoenergetic electrons with energies between 20 and 100 keV with energy fluxes of about 11 ergs cm-2s -•. We have derived the column densities of H2, H, CH4, and C2H2 above the altitudes of peak energy deposition. For methane column densities similar to those determined from IUE and Hubble Space Telescope H2 spectral data, we find that for our standard model, the most likely electron energies are in the 45-55 keV range. For the enhanced eddy diffusion models the energies are lower. We present ion density profiles, H density profiles, and production profiles for the most important H2 and H emissions. The predicted H column densities are in the range (1 -6) x 10 •8 cm -2 for the standard model and are smaller for the enhanced eddy diffusion models. We find that the temperatures near the altitude of peak energy deposition vary from 160 to 200 K and are significantly lower than those derived from rotational analyses of auroral H2 emissions, which average 400-500 K. This indicates that the auroral thermosphere is considerably warmer than those at lower latitudes that were measured by the Voyager spacecraft or the Galileo probe.

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Dissociative Recombination of Molecular Ions

Cited by 25 publications

References 66 publications

Ion‐neutral chemistry model of the lower ionosphere of Mars

Ion‐neutral chemistry model of the lower ionosphere of Mars

Meteoric Ions in the Ionosphere of Jupiter

Chemistry of the Jovian auroral ionosphere

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