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

Su, Wey-Wey

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

Description

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

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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