First-principles calculations of far-wing absorption in He-broadened CO ₂ infrared spectra
- 1Laboratoire de Météorologie Dynamique, IPSL, Sorbonne Université, École Normale Supérieure, Université PSL, École polytechnique, Institut Polytechnique de Paris, CNRS
Abstract
We report theoretical predictions and modeling of the far-wing absorption of CO ₂ broadened by He over a wide temperature range (200–1000 K), which are relevant for exoplanet atmosphere studies. Accurate modeling of He-broadened CO ₂ absorption is essential for opacity calculations used to characterize the composition, structure, and climate of exoplanet atmospheres. In particular, the strong CO ₂ band at 4.3 µm has been clearly identified in the spectra of several exoplanets observed with the James Webb Space Telescope (JWST). Requantized classical molecular dynamics simulations were first performed to predict absorption in the far wings of the 4.3 µm band of CO ₂ . The resulting predictions show excellent agreement with available experimental data at room temperature. The theoretical predictions and measured data were then used to parameterize an impact energy-corrected sudden model, which allowed us to accurately reproduce the far-wing absorption of He-broadened CO ₂ in several infrared spectral regions over the 200–1000 K temperature range. Finally, for applications to exoplanet atmosphere opacity calculations, we derived temperature-dependent χ -factor corrections that account for the sub-Lorentzian behavior of the far wing of the major infrared bands of CO ₂ .
Versions
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BibTeX
@article{tran2026firstprinciples,
title = {{First-principles calculations of far-wing absorption in He-broadened CO ₂ infrared spectra}},
author = {Ha Tran and Emile Ducreux},
journal = {Astronomy \& Astrophysics},
year = {2026},
month = oct,
doi = {10.1051/0004-6361/202662323},
url = {https://www.aanda.org/10.1051/0004-6361/202662323},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - First-principles calculations of far-wing absorption in He-broadened CO ₂ infrared spectra
AU - Ha Tran
AU - Emile Ducreux
PY - 2026
DA - 2026/10/29
JO - Astronomy & Astrophysics
DO - 10.1051/0004-6361/202662323
UR - https://www.aanda.org/10.1051/0004-6361/202662323
AB - We report theoretical predictions and modeling of the far-wing absorption of CO ₂ broadened by He over a wide temperature range (200–1000 K), which are relevant for exoplanet atmosphere studies. Accurate modeling of He-broadened CO ₂ absorption is essential for opacity calculations used to characterize the composition, structure, and climate of exoplanet atmospheres. In particular, the strong CO ₂ band at 4.3 µm has been clearly identified in the spectra of several exoplanets observed with the James Webb Space Telescope (JWST). Requantized classical molecular dynamics simulations were first performed to predict absorption in the far wings of the 4.3 µm band of CO ₂ . The resulting predictions show excellent agreement with available experimental data at room temperature. The theoretical predictions and measured data were then used to parameterize an impact energy-corrected sudden model, which allowed us to accurately reproduce the far-wing absorption of He-broadened CO ₂ in several infrared spectral regions over the 200–1000 K temperature range. Finally, for applications to exoplanet atmosphere opacity calculations, we derived temperature-dependent χ -factor corrections that account for the sub-Lorentzian behavior of the far wing of the major infrared bands of CO ₂ .
SN - 0004-6361
SN - 1432-0746
ER -