Photodissociation of O2 and CO2 from vibrationally excited states at high temperatures

Koshi, Mitsuo; Yoshimura, Masabumi; Matsui, Hiroyuki

doi:10.1016/0009-2614(91)90248-8

Cited by 24 publications

(16 citation statements)

References 23 publications

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“…3 using the method described in the text and the parameters in Table I (solid line). Included in the gure are the results reported by Hartinger et al 14 (dashed line) and data taken from Koshi et al 21 (solid circles).…”

Section: Resultsmentioning

confidence: 97%

“…Absorptivity for O 2 determ ined from the raw transmittance data using the method described in the text. Included in the gure are the results reported by Hartinger et al 14 (dashed line) and data taken from Koshi et al 21 (solid circles). The dotted line is the function from Davidson et al 18 for k in atm 21 cm 2 1 converted to a in cm 2 /molecule.…”

Section: Resultsmentioning

confidence: 97%

“…However, they report that both species exhibit m arked temperature dependence in their absorptivity at this wavelength. The absorptivity of oxygen at ambient and elevated temperature at this wavelength has been well studied, [15][16][17][18][19][20] Koshi et al 21 report effective absorptivity values for O 2 and CO 2 at 193 nm in ver y dilute mixtures measured indirectly behind shock waves in a temperature range of 1200 -2400 8C. They report that a 5 9 3 10 2 20 cm 2 / molecule for O 2 at 1500 8C and a 5 4 3 10 220 cm 2 / molecule for CO 2 at 1500 8C.…”

Section: Introductionmentioning

confidence: 99%

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Absorptivity of Carbon Dioxide and Molecular Oxygen at 193 nm at High Temperatures up to 1600 °C

Rice

Hanush

2002

Appl Spectrosc

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The absorptivity of CO2 and O2 at 193 nm over the temperature range of 900–1600 °C is reported. The data were collected in a flow-type tube furnace using an ArF excimer laser at the light source. CO2 was mixed at 5% by volume in N2 and O2 was examined at 5% and 10%. The internal transmittance of a 1-meter externally heated absorption cell was measured. The results establish a value for the absorptivity, α, for CO2 ranging as high as 2.35 × 10−19 cm2/molecule at 1600 °C. For O2, the absorptivity is 1.81 × 10−19 cm2/molecule at 1600 °C. The results partially agree with those reported in the literature recently by others at 1000 °C and 193 nm and extend those data to higher temperatures; however, the agreement is far from exact. The results are inconsistent with the higher temperature, 1500–2500 °C, values inferred by others from indirect measurements for these two species.

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Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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Absorptivity of Carbon Dioxide and Molecular Oxygen at 193 nm at High Temperatures up to 1600 °C

Rice

Hanush

2002

Appl Spectrosc

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“…In contrast to the many studies of the VUV photodissociation of CO 2 , [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] where absorption cross sections from the a) Current address: Center for Free-Electron Laser Science, DESY, Notkestrasse 85, 22607 Hamburg, Germany. b) Email: reisler@usc.edu ground vibrational state are large, very little is known about the photodissociation at energies closer to the lowest dissociation threshold to O( 3 P) + CO(X 1 Σ + ), which is just above the band origins of the lowest excited singlet states, A 1 B 2 and B 1 A 2 .…”

Section: Introductionmentioning

confidence: 99%

Temperature dependence of the photodissociation of CO2 from high vibrational levels: 205-230 nm imaging studies of CO(X1Σ+) and O(3P, 1D) products

Sutradhar

Samanta

et al. 2017

The Journal of Chemical Physics

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The 205-230 nm photodissociation of vibrationally excited CO at temperatures up to 1800 K was studied using Resonance Enhanced Multiphoton Ionization (REMPI) and time-sliced Velocity Map Imaging (VMI). CO molecules seeded in He were heated in an SiC tube attached to a pulsed valve and supersonically expanded to create a molecular beam of rotationally cooled but vibrationally hot CO. Photodissociation was observed from vibrationally excited CO with internal energies up to about 20 000 cm, and CO(XΣ), O(P), and O(D) products were detected by REMPI. The large enhancement in the absorption cross section with increasing CO vibrational excitation made this investigation feasible. The internal energies of heated CO molecules that absorbed 230 nm radiation were estimated from the kinetic energy release (KER) distributions of CO(XΣ) products in v″ = 0. At 230 nm, CO needs to have at least 4000 cm of rovibrational energy to absorb the UV radiation and produce CO(XΣ) + O(P). CO internal energies in excess of 16 000 cm were confirmed by observing O(D) products. It is likely that initial absorption from levels with high bending excitation accesses both the AB and BA states, explaining the nearly isotropic angular distributions of the products. CO(XΣ) product internal energies were estimated from REMPI spectroscopy, and the KER distributions of the CO(XΣ), O(P), and O(D) products were obtained by VMI. The CO product internal energy distributions change with increasing CO temperature, suggesting that more than one dynamical pathway is involved when the internal energy of CO (and the corresponding available energy) increases. The KER distributions of O(D) and O(P) show broad internal energy distributions in the CO(XΣ) cofragment, extending up to the maximum allowed by energy but peaking at low KER values. Although not all the observations can be explained at this time, with the aid of available theoretical studies of CO VUV photodissociation and O + CO recombination, it is proposed that following UV absorption, the two lowest lying triplet states, aB and bA, and the ground electronic state are involved in the dynamical pathways that lead to product formation.

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“…Some high-temperature measurements have been performed in the past but only at a few wavelengths [18,19]. These measurements were limited to a narrow range of wavelengths and do not provide complete spectra.…”

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confidence: 99%

VUV-absorption cross section of CO₂at high temperatures and impact on exoplanet atmospheres

Venot

Fray

Bénilan

et al. 2014

BIO Web of Conferences

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Abstract. Ultraviolet (UV) absorption cross sections are an essential ingredient of photochemical atmosphere models. Exoplanet searches have unveiled a large population of short-period objects with hot atmospheres, very different from what we find in our solar system. Transiting exoplanets whose atmospheres can now be studied by transit spectroscopy receive extremely strong UV fluxes and have typical temperatures ranging from 400 to 2500 K. At these temperatures, UV photolysis cross section data are severely lacking. Our goal is to provide high-temperature absorption cross sections and their temperature dependency for important atmospheric compounds. This study is dedicated to CO 2 , which is observed and photodissociated in exoplanet atmospheres. We performed these measurements for the 115 -200 nm range at 300, 410, 480, and 550 K. In the 195 -230 nm range, we worked at seven temperatures between 465 and 800 K. We found that the absorption cross section of CO 2 is very sensitive to temperature, especially above 160 nm. Within the studied range of temperature, the CO 2 cross section can vary by more than two orders of magnitude. This, in particular, makes the absorption of CO 2 significant up to wavelengths as high as 230 nm, while it is negligible above 200 nm at 300 K. To investigate the influence of these new data on the photochemistry of exoplanets, we implemented the measured cross section into a 1D photochemical model. The model predicts that accounting for this temperature dependency of CO 2 cross section can affect the computed abundances of NH 3 , CO 2 , and CO by one order of magnitude in the atmospheres of hot Jupiter and hot Neptune.

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Photodissociation of O2 and CO2 from vibrationally excited states at high temperatures

Cited by 24 publications

References 23 publications

Absorptivity of Carbon Dioxide and Molecular Oxygen at 193 nm at High Temperatures up to 1600 °C

Absorptivity of Carbon Dioxide and Molecular Oxygen at 193 nm at High Temperatures up to 1600 °C

Temperature dependence of the photodissociation of CO2 from high vibrational levels: 205-230 nm imaging studies of CO(X1Σ+) and O(3P, 1D) products

VUV-absorption cross section of CO₂at high temperatures and impact on exoplanet atmospheres

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Photodissociation of O2 and CO2 from vibrationally excited states at high temperatures

Cited by 24 publications

References 23 publications

Absorptivity of Carbon Dioxide and Molecular Oxygen at 193 nm at High Temperatures up to 1600 °C

Absorptivity of Carbon Dioxide and Molecular Oxygen at 193 nm at High Temperatures up to 1600 °C

Temperature dependence of the photodissociation of CO2 from high vibrational levels: 205-230 nm imaging studies of CO(X1Σ+) and O(3P, 1D) products

VUV-absorption cross section of CO2at high temperatures and impact on exoplanet atmospheres

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VUV-absorption cross section of CO₂at high temperatures and impact on exoplanet atmospheres