Emission cross section of O I (135.6 nm) at 100 eV resulting from electron‐impact dissociative excitation of O<sub>2</sub>

Norén, C.; Kanik, I.; Ajello, J. M.; McCartney, P.; Makarov, O. P.; McClintock, W. E.; Drake, Virginia Ann

doi:10.1029/2000gl012577

Cited by 16 publications

(14 citation statements)

References 15 publications

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“…Wells et al [1971] found the cross section for dissociative excitation to be 1.1 Â 10 À17 cm 2 at 100 eV. We can now correct the Ajello [1971] calculation at 100 eV for the current shorter lifetime of 180 ms. We find that the corrected result agrees closely with our more accurate measurement of the OI(135.6 nm) emission cross section at 100 eV, described in section 3 and by Noren et al [2001].…”

Section: Introductionsupporting

confidence: 88%

Electron impact dissociative excitation of O₂: 2. Absolute emission cross sections of the OI(130.4 nm) and OI(135.6 nm) lines

et al. 2003

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[1] In this work, we report the OI(135.6 nm) absolute emission cross section resulting from the long-lived (180 ms) OI( 5 S ! 3 P) transition from dissociative excitation of O 2 . From the ratio of the integrated intensities of the OI(135.6 nm) and OI(130.4 nm) features and from the absolute emission cross section for the OI(130.4 nm) emission feature from electron impact dissociative excitation of O 2 at 100 eV, the absolute emission cross section for the OI(135.6 nm) feature was determined to be 6.4 Â 10 À18 cm 2 at 100 eV. Electron impactinduced optical excitation functions for optically allowed transitions at 115.2 nm and 130.4 nm and for an optically forbidden transition at 135.6 nm were also obtained over the electron impact energy range 0-600 eV. The OI(135.6 nm) emission cross section was measured in the laboratory utilizing a large collision chamber (1.5 m in diameter). Electrons were produced with an electrostatically focusing gun with a large focal length (50 cm). The OI(130.4 nm, 135.6 nm) excitation functions were put on an absolute scale as described in the text, and the OI(135.6 nm)/OI(130.4 nm) ratio was determined for the entire energy range (0-600 eV). The atomic O UV emission cross sections from dissociative excitation of O 2 can be used to model the recent Hubble Space Telescope observations of OI(130.4 nm) and OI(135.6 nm) intensities from Ganymede [Feldman et al., 2000] and Europa [Hall et al., 1995[Hall et al., , 1998].

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Section: Introductionsupporting

confidence: 88%

Electron impact dissociative excitation of O₂: 2. Absolute emission cross sections of the OI(130.4 nm) and OI(135.6 nm) lines

et al. 2003

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“…We have successfully constructed a large vacuum system apparatus for measuring the emission cross sections of two of the strongest optically forbidden transitions found in the Mars airglow: O i (135.6 nm; reported in this paper) and the Cameron bands in the MUV (in preparation). The experimental apparatus for emission cross sections has been discussed in detail previously (Ajello et al, ; Kanik et al, ; Noren et al, ). We have published the initial work 10 years ago on O i ( 135.6 nm) from dissociation of O 2 using the Cassini UVIS flight‐spare (Kanik et al, ; Makarov et al, ).…”

Section: Experimental Apparatusmentioning

confidence: 99%

UV Study of the Fourth Positive Band System of CO and O i 135.6 nm From Electron Impact on CO and CO₂

et al. 2019

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We have measured the 30 and 100 eV far ultraviolet (FUV) emission cross sections of the optically allowed Fourth Positive Group (4PG) band system (A 1 Π → X 1 Σ + ) of CO and the optically forbidden O ( 5 S o → 3 P) 135.6 nm atomic transition by electron-impact-induced-fluorescence of CO and CO 2 . We present a model excitation cross section from threshold to high energy for the A 1 Π state, including cascade by electron impact on CO. The A 1 Π state is perturbed by triplet states leading to an extended FUV glow from electron excitation of CO. We derive a model FUV spectrum of the 4PG band system from dissociative excitation of CO 2 , an important process observed on Mars and Venus. Our unique experimental setup consists of a large vacuum chamber housing an electron gun system and the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission Imaging Ultraviolet Spectrograph optical engineering unit, operating in the FUV (110-170 nm). The determination of the total O I ( 5 S o ) at 135.6 nm emission cross section is accomplished by measuring the cylindrical glow pattern of the metastable emission from electron impact by imaging the glow intensity about the electron beam from nominally zero to~400 mm distance from the electron beam. The study of the glow pattern of O I (135.6 nm) from dissociative excitation of CO and CO 2 indicates that the O I ( 5 S o ) state has a kinetic energy of~1 eV by modeling the radial glow pattern with the published lifetime of 180 μs for the O I ( 5 S o ) state.Plain Language Summary Both Mars and Venus have upper atmospheres that are similar in composition: mostly CO 2 , CO, and N 2 are dominant molecular gases, with nearly identical UV spectra. The modeling studies of atmospheric UV emissions cannot presently be accurately conducted to the same accuracy as the planetary UV measurements, which avail themselves with state-of-the-art calibrated spectrographs. This dichotomy in accuracy between planetary observation and model occurs because the atomic and molecular emission cross sections with uncertainties of certain transitions are greater than 100%. Furthermore, the analysis is complicated by the spectral blending of the various emissions of the low-resolution spectral spaceborne instruments. We present in this paper a UV laboratory instrument unique in the world at the University of Colorado that can measure for the first time the excitation mechanisms with accurate emission cross sections of both allowed and optically forbidden transitions that are occurring in a planetary atmosphere. Key Points: • We measured 30 and 100 eV emission cross sections of Fourth Positive band system of CO and O I (135.6 nm) from electron impact on CO and CO 2 • We conducted a laboratory experiment measuring single-scattering electron-impactinduced-fluorescence FUV spectra from excitation of CO and CO 2 • Fragment kinetic energy measurement for O I ( 5 S o ) atoms found to be around~1 eV from both CO and CO 2 molecular dissociation Correspondence to: et al. (2019). UV study of the Fourth Positive band system ...

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“…The experimental apparatus for emission cross sections has been discussed in detail previously [ Noren et al , ; Kanik et al , ]. We have previously published the work on O i (135.6 nm) from dissociation of O 2 using the Cassini UVIS (Ultraviolet Imaging Spectrograph) [ Kanik et al , ; Makarov et al , ].…”

Section: Experimental Apparatusmentioning

confidence: 99%

Electron impact study of the 100 eV emission cross section and lifetime of the Lyman‐Birge‐Hopfield band system of N₂: Direct excitation and cascade

et al. 2017

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We have measured the 100 eV emission cross section of the optically forbidden Lyman‐Birge‐Hopfield (LBH) band system (a1Πg → X1Σ+g) of N2 by electron‐impact‐induced fluorescence. Using a large (1.5 m diameter) vacuum chamber housing an electron gun system and the Mars Atmosphere and Volatile EvolutioN mission Imaging Ultraviolet Spectrograph optical engineering model, we have obtained calibrated spectral measurements of the LBH band system from 115 to 175 nm over a range of lines of sight to capture all of the optical emissions. These measurements represent the first experiment to directly isolate in the laboratory single‐scattering electron‐impact‐induced fluorescence from both direct excitation of the a1Πg state and cascading contributions to the a1Πg state (a′1Σ−u and w1Δu → a1Πg → X1Σ+g). The determination of the total LBH emission cross section is accomplished by measuring the entire cylindrical glow pattern of the metastable emission from electron impact by imaging lines of sight that measure the glow intensity from zero to ~400 mm radial distance and calculating the ratio of the integrated intensity from the LBH glow pattern to that of a simultaneously observed optically allowed transition with a well‐established cross section: Ni 120.0 nm. The “direct” emission cross section of the a1Πg state at 100 eV was determined to be σemdir = (6.41 ± 1.3) × 10−18 cm2. An important observation from the glow pattern behavior is that the total (direct + cascading) emission cross section is pressure dependent due to collision‐induced cascade transitions between close‐lying electronic states.

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Emission cross section of O I (135.6 nm) at 100 eV resulting from electron‐impact dissociative excitation of O₂

Cited by 16 publications

References 15 publications

Electron impact dissociative excitation of O₂: 2. Absolute emission cross sections of the OI(130.4 nm) and OI(135.6 nm) lines

Electron impact dissociative excitation of O₂: 2. Absolute emission cross sections of the OI(130.4 nm) and OI(135.6 nm) lines

UV Study of the Fourth Positive Band System of CO and O i 135.6 nm From Electron Impact on CO and CO₂

Electron impact study of the 100 eV emission cross section and lifetime of the Lyman‐Birge‐Hopfield band system of N₂: Direct excitation and cascade

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Emission cross section of O I (135.6 nm) at 100 eV resulting from electron‐impact dissociative excitation of O2

Cited by 16 publications

References 15 publications

Electron impact dissociative excitation of O2: 2. Absolute emission cross sections of the OI(130.4 nm) and OI(135.6 nm) lines

Electron impact dissociative excitation of O2: 2. Absolute emission cross sections of the OI(130.4 nm) and OI(135.6 nm) lines

UV Study of the Fourth Positive Band System of CO and O i 135.6 nm From Electron Impact on CO and CO2

Electron impact study of the 100 eV emission cross section and lifetime of the Lyman‐Birge‐Hopfield band system of N2: Direct excitation and cascade

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Emission cross section of O I (135.6 nm) at 100 eV resulting from electron‐impact dissociative excitation of O₂

Electron impact dissociative excitation of O₂: 2. Absolute emission cross sections of the OI(130.4 nm) and OI(135.6 nm) lines

Electron impact dissociative excitation of O₂: 2. Absolute emission cross sections of the OI(130.4 nm) and OI(135.6 nm) lines

UV Study of the Fourth Positive Band System of CO and O i 135.6 nm From Electron Impact on CO and CO₂

Electron impact study of the 100 eV emission cross section and lifetime of the Lyman‐Birge‐Hopfield band system of N₂: Direct excitation and cascade