Laboratory Study of the Cameron Bands and UV Doublet in the Middle Ultraviolet 180–300 nm by Electron Impact upon CO<sub>2</sub> with Application to Mars

Lee, Rena A.; Ajello, J. M.; Malone, C. P.; Evans, J. Scott; Veibell, V.; Holsclaw, G. M.; McClintock, William E.; Hoskins, Alan; Jain, Sonal; Gérard, Jean‐Claude; Aryal, Saurav; Schneider, Nicholas M.

doi:10.3847/1538-4357/ac88c8

Cited by 5 publications

(3 citation statements)

References 69 publications

(188 reference statements)

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“…In the past we have constructed a large (1.5 m-diameter) vacuum system apparatus for measuring the emission cross sections of the strongest optically forbidden transitions found in solar system planetary atmosphere airglow: N 2 LBH (Ajello et al, 2017), O I 135.6 nm from O 2 (Kanik et al, 2003;Noren et al, 2001), and O I 135.6 nm from CO and CO 2 (Ajello et al, 2019), as well as the Cameron bands from CO and CO 2 in the middle ultraviolet (MUV) (Lee et al, 2019).…”

Section: Experimental Apparatusmentioning

confidence: 99%

The UV Spectrum of the Lyman‐Birge‐Hopfield Band System of N₂ Induced by Cascading from Electron Impact

et al. 2020

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We have measured in the laboratory the far ultraviolet (FUV: 125.0-170.0 nm) cascade-induced spectrum of the Lyman-Birge-Hopfield (LBH) band system (a 1 Π g →X 1 Σ þ g ) of N 2 excited by 30-200 eV electrons. The cascading transition begins with two processes: radiative and collision-induced electronic transitions (CIETs) involving two states (a′ 1 Σ − u and w 1 Δ u → a 1 Π g ), which are followed by a cascade induced transition a 1 Π g →X 1 Σ þ g at the single-scattering pressures employed here. Direct excitation to the a-state produces a confined LBH spectral glow pattern around an electron beam. We have spatially resolved the electron-induced glow pattern from an electron beam colliding with N 2 at radial distances of 0-400 mm at three gas pressures. This imaging measurement is the first to isolate spectral measurements in the laboratory of single-scattering electron-impact-induced fluorescence from two LBH emission processes: direct excitation, which is strongest in emission near the electron beam axis; and cascading-induced, which is dominant far from the electron beam axis. The vibrational populations for vibrational levels from v′ = 0-2 of the a 1 Π g state are enhanced by radiative cascade and CIETs, and the emission cross sections of the LBH band system for direct and cascading-induced excitation are provided at 40, 50, 100, and 200 eV.

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Section: Experimental Apparatusmentioning

confidence: 99%

The UV Spectrum of the Lyman‐Birge‐Hopfield Band System of N₂ Induced by Cascading from Electron Impact

et al. 2020

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“…There is a small amount of additional emission present at 313.47 nm in the IUVS limb spectra, which is at the same wavelength as an O II emission line (Wenåker, 1990) and we add that separately to the regression fit of the IUVS limb data. Although IUVS does not have the spectral resolution to explicitly identify this weak feature as O II, we note that this feature is also present in laboratory observations of electron impact on CO 2 (Lee et al, 2022; their Figure 5).…”

Section: Data Analysis Approachmentioning

confidence: 82%

MAVEN/IUVS Observations of OH Prompt Emission: Daytime Water Vapor in the Thermosphere of Mars

Stevens,

Cangi,

Deighan

et al. 2024

JGR Planets

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We report the highest altitude detection of water vapor on Mars to date. The daytime limb observations by the Imaging Ultraviolet Spectrograph (IUVS) on the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft are of hydroxyl (OH) prompt emission near 308 nm, which is excited directly from the photodissociation of water vapor by the solar Lyman‐α flux. Average IUVS daytime water vapor densities near 130 km are 3 × 107 cm−3 around perihelion. The water vapor densities diurnally vary with a peak near midday and no detection at sunrise and sunset. To evaluate the large daytime water vapor densities for self‐consistency, we also report the simultaneous observation of OH solar fluorescence emission near 308 nm in the thermosphere, which enables the retrieval of OH densities. Using a one‐dimensional photochemical model initialized with the daytime IUVS water vapor densities, modeled peak OH densities are in good agreement with the observed IUVS peak OH densities. Because the observed thermospheric temperatures are controlled by solar insolation and cross the water frost point during the day, we suggest that the IUVS observed water vapor is created by the daily sublimation of water ice particles supplied from below. We discuss the implications of the IUVS observations on the present day loss of water vapor from Mars in the form of atomic hydrogen.

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“…For the purposes of measuring the CO concentration, the CO Angstrom band line at 519.6 nm (B 1 Σ − A 1 π) [1] is used. As for the CO 2 concentration, the UV Doublet ( B2 Σ + u − X2 Π g ) at 288.3 and 289.6 nm is used [2] . These were the most dominant peaks of the CO and CO 2 spectra present and were used to calculate the CO:CO 2 intensity ratio.…”

Section: Resultsmentioning

confidence: 99%

Plasma enhanced CO2 recombination in EUV drive lasers

Herschberg

Bartlett

Crouse

et al. 2023

Optical and EUV Nanolithography XXXVI

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During plasma excitation of CO2 molecules in drive lasers, up to 60% of the CO2 decomposes into CO. Typically, Au is used as a catalyst to preferentially recombine CO and O radicals into CO2. By adding a secondary, microwave driven plasma to the system at the Au catalyst, O atoms can be stripped away from contaminants created in the laser such as Ox and NOx compounds. It is hypothesized that this will decrease the CO:CO2 ratio, which increases overall laser efficiency. This work serves as a status update on the measurement of CO:CO2 ratios for 4 tests: 1) control, 2) with Au catalyst installed, 3) with secondary plasma active, and 4) with Au catalyst installed and secondary plasma active.

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Laboratory Study of the Cameron Bands and UV Doublet in the Middle Ultraviolet 180–300 nm by Electron Impact upon CO₂ with Application to Mars

Cited by 5 publications

References 69 publications

The UV Spectrum of the Lyman‐Birge‐Hopfield Band System of N₂ Induced by Cascading from Electron Impact

The UV Spectrum of the Lyman‐Birge‐Hopfield Band System of N₂ Induced by Cascading from Electron Impact

MAVEN/IUVS Observations of OH Prompt Emission: Daytime Water Vapor in the Thermosphere of Mars

Plasma enhanced CO2 recombination in EUV drive lasers

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Laboratory Study of the Cameron Bands and UV Doublet in the Middle Ultraviolet 180–300 nm by Electron Impact upon CO2 with Application to Mars

Cited by 5 publications

References 69 publications

The UV Spectrum of the Lyman‐Birge‐Hopfield Band System of N2 Induced by Cascading from Electron Impact

The UV Spectrum of the Lyman‐Birge‐Hopfield Band System of N2 Induced by Cascading from Electron Impact

MAVEN/IUVS Observations of OH Prompt Emission: Daytime Water Vapor in the Thermosphere of Mars

Plasma enhanced CO2 recombination in EUV drive lasers

Contact Info

Product

Resources

About

Laboratory Study of the Cameron Bands and UV Doublet in the Middle Ultraviolet 180–300 nm by Electron Impact upon CO₂ with Application to Mars

The UV Spectrum of the Lyman‐Birge‐Hopfield Band System of N₂ Induced by Cascading from Electron Impact

The UV Spectrum of the Lyman‐Birge‐Hopfield Band System of N₂ Induced by Cascading from Electron Impact