H2-induced pressure broadening and pressure shift in the P-branch of the ν3 band of CH4 from 300 to 655 K

Ehsan Gharib-Nezhad; Alan N. Heays; Hans A. Bechtel; James R. Lyons

doi:10.1016/j.jqsrt.2019.106649

H₂-induced pressure broadening and pressure shift in the P-branch of the ν₃ band of CH₄ from 300 to 655 K

Ehsan Gharib-Nezhad, Alan N. Heays, Hans A. Bechtel, James R. Lyons

CLAS-NS: Earth and Space Exploration, School of (SESE)

Research output: Contribution to journal › Article › peer-review

4 Scopus citations

Abstract

For accurate modelling of observations of exoplanet atmospheres, quantification of the pressure broadening of infrared absorption lines for and by a variety of gases at elevated temperatures is needed. High-resolution high-temperature H₂-pressure-broadened spectra are recorded for the CH₄ ν₃-band P-branch. Measured linewidths for 143 transitions between 2840 and 3000 cm⁻¹ with temperature and pressures ranging between 300 and 655 K, and 10 and 933 Torr, respectively, were used to find rotation- and tetrahedral-symmetry-dependent coefficients for pressure and temperature broadening and pressure-induced lineshifts. The new pressure-broadening data will be useful in radiative-transfer models for retrieving the properties of observed expolanet atmospheres.

Original language	English (US)
Article number	106649
Journal	Journal of Quantitative Spectroscopy and Radiative Transfer
Volume	239
DOIs	https://doi.org/10.1016/j.jqsrt.2019.106649
State	Published - Dec 2019

Keywords

Exoplanetary atmospheres
High-temperature FTIR spectroscopy
High-temperature pressure-induced collisional broadening and shift
Hydrogen-dominant atmospheres
Lorentzian linewidth coefficients
Methane (CH)

ASJC Scopus subject areas

Radiation
Atomic and Molecular Physics, and Optics
Spectroscopy

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@article{2bdbb787b1a0418285f3bc48a13b47a8,

title = "H2-induced pressure broadening and pressure shift in the P-branch of the ν3 band of CH4 from 300 to 655 K",

abstract = "For accurate modelling of observations of exoplanet atmospheres, quantification of the pressure broadening of infrared absorption lines for and by a variety of gases at elevated temperatures is needed. High-resolution high-temperature H2-pressure-broadened spectra are recorded for the CH4 ν3-band P-branch. Measured linewidths for 143 transitions between 2840 and 3000 cm−1 with temperature and pressures ranging between 300 and 655 K, and 10 and 933 Torr, respectively, were used to find rotation- and tetrahedral-symmetry-dependent coefficients for pressure and temperature broadening and pressure-induced lineshifts. The new pressure-broadening data will be useful in radiative-transfer models for retrieving the properties of observed expolanet atmospheres.",

keywords = "Exoplanetary atmospheres, High-temperature FTIR spectroscopy, High-temperature pressure-induced collisional broadening and shift, Hydrogen-dominant atmospheres, Lorentzian linewidth coefficients, Methane (CH)",

author = "Ehsan Gharib-Nezhad and Heays, {Alan N.} and Bechtel, {Hans A.} and Lyons, {James R.}",

note = "Funding Information: We kindly thank Glenn Stark, David Wright, Adam Schneider, and the Arizona State University exoplanet group for many useful discussions as well as Richard Freedman and Mark Marley for their enthusiasm for us to get these laboratory data out the door. E.G.N. especially thanks Mike Line for numerous invaluable discussions during this work. Mike is amazing. E.G.N. acknowledges funding from the GRSP research grant from the Arizona State University Graduate office program award XH51027 . A.N.H.{\textquoteright}s research was supported by an appointment to the NASA Postdoctoral Program at Arizona State University and the NASA Astrobiology Institute , administered by Universities Space Research Association under contract with NASA. This research used resources of the Advanced Light Source, which is a DOE Office of Science User Facility under contract no. DE-AC02-05CH11231 . Finally, we would like to thank the anonymous reviewers for their thoughtful and constructive suggestions. ",

year = "2019",

month = dec,

doi = "10.1016/j.jqsrt.2019.106649",

language = "English (US)",

volume = "239",

journal = "Journal of Quantitative Spectroscopy and Radiative Transfer",

issn = "0022-4073",

publisher = "Elsevier Limited",

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AU - Gharib-Nezhad, Ehsan

AU - Heays, Alan N.

AU - Bechtel, Hans A.

AU - Lyons, James R.

N1 - Funding Information: We kindly thank Glenn Stark, David Wright, Adam Schneider, and the Arizona State University exoplanet group for many useful discussions as well as Richard Freedman and Mark Marley for their enthusiasm for us to get these laboratory data out the door. E.G.N. especially thanks Mike Line for numerous invaluable discussions during this work. Mike is amazing. E.G.N. acknowledges funding from the GRSP research grant from the Arizona State University Graduate office program award XH51027 . A.N.H.’s research was supported by an appointment to the NASA Postdoctoral Program at Arizona State University and the NASA Astrobiology Institute , administered by Universities Space Research Association under contract with NASA. This research used resources of the Advanced Light Source, which is a DOE Office of Science User Facility under contract no. DE-AC02-05CH11231 . Finally, we would like to thank the anonymous reviewers for their thoughtful and constructive suggestions.

PY - 2019/12

Y1 - 2019/12

N2 - For accurate modelling of observations of exoplanet atmospheres, quantification of the pressure broadening of infrared absorption lines for and by a variety of gases at elevated temperatures is needed. High-resolution high-temperature H2-pressure-broadened spectra are recorded for the CH4 ν3-band P-branch. Measured linewidths for 143 transitions between 2840 and 3000 cm−1 with temperature and pressures ranging between 300 and 655 K, and 10 and 933 Torr, respectively, were used to find rotation- and tetrahedral-symmetry-dependent coefficients for pressure and temperature broadening and pressure-induced lineshifts. The new pressure-broadening data will be useful in radiative-transfer models for retrieving the properties of observed expolanet atmospheres.

AB - For accurate modelling of observations of exoplanet atmospheres, quantification of the pressure broadening of infrared absorption lines for and by a variety of gases at elevated temperatures is needed. High-resolution high-temperature H2-pressure-broadened spectra are recorded for the CH4 ν3-band P-branch. Measured linewidths for 143 transitions between 2840 and 3000 cm−1 with temperature and pressures ranging between 300 and 655 K, and 10 and 933 Torr, respectively, were used to find rotation- and tetrahedral-symmetry-dependent coefficients for pressure and temperature broadening and pressure-induced lineshifts. The new pressure-broadening data will be useful in radiative-transfer models for retrieving the properties of observed expolanet atmospheres.

KW - Exoplanetary atmospheres

KW - High-temperature FTIR spectroscopy

KW - High-temperature pressure-induced collisional broadening and shift

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KW - Lorentzian linewidth coefficients

KW - Methane (CH)

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