University of Illinois Urbana-Champaign

Line Mixing Study Of Carbon Monoxide Broadened By Nitrogen, Helium, And Hydrogen

Su, Wey-Wey

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FE08_1.pptx
6020.pdf

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https://hdl.handle.net/2142/116985

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Title
Line Mixing Study Of Carbon Monoxide Broadened By Nitrogen, Helium, And Hydrogen
Author(s)
Su, Wey-Wey
Contributor(s)
  • Hanson, Ronald K.
  • Strand, Christopher L.
  • Ding, Yiming
Issue Date
2022-06-24
Keyword(s)
Lineshapes, collisional effects
Abstract
\begin{wrapfigure}{r}{0pt} \includegraphics[scale=0.49]{H2_LooneyM2EG_lockeda2pr_COH2sRv5_CMpfv2_5varFit_a4is0pt2_Pspread_220222.eps} \end{wrapfigure} Upcoming exoplanet infrared imaging will likely include carbon monoxide (CO) absorption from deeper, higher-pressure regions of larger Jupiter-like exoplanets, with compositions of majority hydrogen (H$_{2}$) and helium (He). However, there have been limited experimental CO spectroscopy studies in H$_{2}$ and He at elevated pressure conditions. We present quantitative, broadband absorbance measurements of the fundamental ro-vibrational band of CO between 1965 and 2235 \wn, in bath gases of nitrogen (N$_{2}$), He, and H$_{2}$. Then, we demonstrate a modeling approach that accurately reflects the effects of line mixing that we observe in the results, utilizing the modified exponential gap (MEG) law with a fitted inter-branch factor. The room-temperature static cell measurements were taken using a narrow-linewidth, broad-scan external-cavity quantum-cascade laser at pressures of 15\textendash35 atm. For CO in H$_{2}$ and He, minor adjustments to the MEG Law were necessary to reproduce the weaker J$''$-dependence of the broadening coefficients relative to that of CO in N$_{2}$. The resulting MEG line mixing model shows improved agreement with the measured spectra across different pressures and broadening partners. Further reduction of the residuals to within approximately 1\% (CO/H$_{2}$, 35 atm) is shown through the fitting of MEG coefficients directly to measured spectra, resulting in relatively small adjustments to each of the coefficients.
Publisher
International Symposium on Molecular Spectroscopy
Type of Resource
text
Genre of Resource
Conference Paper / Presentation
Language
eng
Handle URL
https://hdl.handle.net/2142/116985
DOI
https://doi.org/10.15278/isms.2022.FE08
Copyright and License Information
Copyright 2022 held by the authors

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Abstracts & Presentations - 2022 International Symposium on Molecular Spectroscopy PRIMARY