Total and dissociative photoionization cross sections of N2 from threshold to 107 eV

Samson, James A. R.; Masuoka, Toshio; Pareek, Prem N.; Angel, G.

doi:10.1063/1.452452

Cited by 63 publications

(52 citation statements)

References 31 publications

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“…At wavelengths shorter than 80 nm irradiation, approximately 3-5% of total N 2 molecules experience dissociation. At wavelengths shorter than 66 nm, where the N 2 molecule experiences continuum photoabsorption (23), the photon flux is equal to the N 2 dissociation rates under our optically thick condition and is estimated to be 1-1.5× 10 16 photons∕s, which is consistent with previous measurement (24).…”

Section: Resultssupporting

confidence: 80%

Formation of nitrogenated organic aerosols in the Titan upper atmosphere

Imanaka

Smith

2010

Proc. Natl. Acad. Sci. U.S.A.

107

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Many aspects of the nitrogen fixation process by photochemistry in the Titan atmosphere are not fully understood. The recent Cassini mission revealed organic aerosol formation in the upper atmosphere of Titan. It is not clear, however, how much and by what mechanism nitrogen is incorporated in Titan's organic aerosols. Using tunable synchrotron radiation at the Advanced Light Source, we demonstrate the first evidence of nitrogenated organic aerosol production by extreme ultraviolet-vacuum ultraviolet irradiation of a N 2 ∕CH 4 gas mixture. The ultrahigh-mass-resolution study with laser desorption ionization-Fourier transform-ion cyclotron resonance mass spectrometry of N 2 ∕CH 4 photolytic solid products at 60 and 82.5 nm indicates the predominance of highly nitrogenated compounds. The distinct nitrogen incorporations at the elemental abundances of H 2 C 2 N and HCN, respectively, are suggestive of important roles of H 2 C 2 N∕HCCN and HCN∕CN in their formation. The efficient formation of unsaturated hydrocarbons is observed in the gas phase without abundant nitrogenated neutrals at 60 nm, and this is confirmed by separately using 13 C and 15 N isotopically labeled initial gas mixtures. These observations strongly suggest a heterogeneous incorporation mechanism via short lived nitrogenated reactive species, such as HCCN radical, for nitrogenated organic aerosol formation, and imply that substantial amounts of nitrogen is fixed as organic macromolecular aerosols in Titan's atmosphere.

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Section: Resultssupporting

confidence: 80%

Formation of nitrogenated organic aerosols in the Titan upper atmosphere

Imanaka

Smith

2010

Proc. Natl. Acad. Sci. U.S.A.

107

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“…To illustrate the importance of the dipole interaction in the singly-differential cross section for fast protons, Kim has extracted continuum oscillator strengths df /dEj from known photoionization cross sections for Ar (Berkowitz, 1979) and N, (Berkowitz, 1979;Samson et al, 1987). Then df /dEj was fitted with a linear combination of Gaussian functions…”

Section: Kim's Modelmentioning

confidence: 99%

Electron production in proton collisions with atoms and molecules: energy distributions

1992

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All known data on the energy distribution of secondary electrons from collisions of protons with atoms and molecules have been reviewed and differential cross sections have been collected. The two experimental methods used to obtain the data are discussed and possible sources of error pointed out. Theoretical treatments are reviewed and several methods of checking the consistency of the data are discussed. Two semiempirical models have been chosen to represent the differential cross sections, and parameters for these models are given which fit the average of the experimental data, subject to known constraints. Recommended values of differential cross sections are given for ten target gases by means of these models. All known data on the energy distribution of secondary electrons from collisions of protons with atoms and molecules have been reviewed and differential cross sections have been collected. The two experimental methods used to obtain the data are discussed and possible sources of error pointed out. Theoretical treatments are reviewed and several methods of checking the consistency of the data are discussed. Two semiempirical models have been chosen to represent the differential cross sections, and parameters for these models are given which fit the average of the experimental data, subject to known constraints. Recommended values of differential cross sections are given for ten target gases by means of these models. ©1992

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“…We also consider the double photoionization of O, with the cross-section data taken from Angel and Samson [1988]. The N 2 dissociative photoionization and photoabsorption cross sections are adopted from Stolte et al [1998], Samson et al [1987] and Chan et al [1993a]. For CO 2 , we consider both single and double dissociative photoionization channels, with their cross sections taken from Masuoka [1994], Hitchcock et al [1980] and Siggel et al [1993].…”

Section: Discussionmentioning

confidence: 99%

Suprathermal electron spectra in the Venus ionosphere

et al. 2011

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[1] In this study, a multistream kinetic model is used to derive the suprathermal electron intensity in the Venus ionosphere, to be compared with the observations made by the Analyzer of Space Plasmas and Energetic Atoms (ASPERA-4) Electron Spectrometer (ELS) instrument onboard Venus Express (VEx) on 18 May 2006. Input parameters of the model are chosen to be consistent with the detailed ephemeris information. We consider two cases for the magnetic field line configuration. The first assumes vertical magnetic field lines, while in the second the configuration is consistent with the VEx Magnetometer (MAG) measurements for that particular orbit. The model calculations suggest that the energy spectrum of suprathermal electrons not only depends on the local photoelectron production but is also strongly influenced by transport as well as energy degradation. We confirm the postulation of Coates et al. (2008) (2008). The model results indicate that the condition of local equilibrium is satisfied for suprathermal electrons below ∼155 km on Venus. However, transport becomes effective at higher altitudes, significantly altering the secondary electron production rate and leading to strongly anisotropic suprathermal electron flow. For the case with the MAG-derived, slanted magnetic field configuration, we make a data-model comparison in terms of both the absolute magnitude of the suprathermal electron intensity and the appearance of spectral peaks. The comparison suggests that the actual magnetic field lines are probably inclined more vertically than a simple extrapolation from the MAG measurements.

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Total and dissociative photoionization cross sections of N2 from threshold to 107 eV

Cited by 63 publications

References 31 publications

Formation of nitrogenated organic aerosols in the Titan upper atmosphere

Formation of nitrogenated organic aerosols in the Titan upper atmosphere

Electron production in proton collisions with atoms and molecules: energy distributions

Suprathermal electron spectra in the Venus ionosphere

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