Ft-ir Measurements Of Crosssections For Trans-2-butene In The 7-15 Μm Region At 160-297 K For Titan’s Atmosphere

Sung, Keeyoon

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https://hdl.handle.net/2142/116531 Copy

Description

Title

Ft-ir Measurements Of Crosssections For Trans-2-butene In The 7-15 Μm Region At 160-297 K For Titan’s Atmosphere

Author(s)

Sung, Keeyoon

Contributor(s)

• Nixon, Conor A.
• Lopes, Rosaly M.
• Malaska, Michael
• Steffens, Brendan

Issue Date

2022-06-24

Keyword(s)

Lineshapes, collisional effects

Abstract

We present temperature-dependent cross sections for $\it{trans}$-2-Butene ($\it{trans}$-2-C$_{4}$H$_{8}$: CH$_{3}$-CH=CH-CH$_{3}$) in the 7 - 15 $\mu$m region in support of remote sensing of Titan’s stratosphere. It is one of many C$_{4}$-hydrocarbons predicted to be in detectable abundances in Titan’s atmosphere by photochemical models, but no high-resolution spectroscopy is available in the public databases in the mid-infrared region, let alone at cold temperatures appropriate for Titan. We collected 28 pure and N$_2$-mixture spectra and their corresponding background spectra at temperatures between 160-297 K using a Fourier transform spectrometer (Bruker IFS-125HR) at the Jet Propulsion Laboratory at spectral resolutions between 0.0039 and 0.062 \wn, depending on sample pressures in consideration of line shape resolving power. We obtained transmission spectra by ratioing the sample spectra to their empty-cell spectra, from which several fundamental modes of vibration were identified and updated in comparison to their band centers reported in the literature. We defined two distinct spectral regions, each of which contains multiple vibrational bands and hot band features and we measured the temperature-dependent cross sections, and report their integrated cross sections as well. We performed a separate linearity test between the sample absorbance and optical burden for the spectra obtained at various sample pressures. No significant dependence on temperature was observed in the integrated cross sections, which validated our measurements and methodology. Our measured cross sections will provide critical laboratory input toward a search for $\it{trans}$-2-Butene in Titan stratosphere that may be captured in the Cassini/CIRS spectra. To facilitate this, we will report our final results to the public databases, such as HITRAN and GEISA.\footnote{Government support acknowledged.}

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Handle URL

https://hdl.handle.net/2142/116531

DOI

https://doi.org/10.15278/isms.2022.FE09

Copyright and License Information

Copyright 2022 held by the authors

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