Theory of collision-induced absorption for electronic transitions in the atmospherically relevant O2−O2 and O2−N2 pairs

Karman, Tijs

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https://hdl.handle.net/2142/97194 Copy

Description

Title

Theory of collision-induced absorption for electronic transitions in the atmospherically relevant O2−O2 and O2−N2 pairs

Author(s)

Karman, Tijs

Contributor(s)

• Groenenboom, Gerrit
• van der Avoird, Ad

Issue Date

2017-06-21

Keyword(s)

• Lineshapes
• Collisional effects

Abstract

Collision-induced absorption of O$_2-$O$_2$ and O$_2-$N$_2$ pairs is observed in remote sensing of the Earth's atmosphere,_x000d_ and absorption by O$_2-$O$_2$ pairs has been put forward as a biomarker to be observed in exoplanetary transit spectra._x000d_ The relevant electronic transitions, $X~{}^3Sigma_g^- rightarrow a~{}^1Delta_g$ and $X~{}^3Sigma_g^- rightarrow b~{}^1Sigma_g^+$, are electric-dipole forbidden by both spin and spatial selection rules,_x000d_ such that collision-induced absorption represents an important contribution to the absorption._x000d_ _x000d_ We present an emph{ab initio} study of collision-induced absorption for these electronic transitions using quantum-mechanical scattering calculations._x000d_ Two mechanisms for breaking the spin-symmetry are taken into account:_x000d_ intramolecular spin-orbit coupling and intermolecular exchange interactions._x000d_ We find and explain qualitative differences in the line shape and temperature dependence of the absorption due to these mechanisms._x000d_ The contributions of these mechanisms furthermore explain qualitative differences between the atmospherically relevant O$_2-$O$_2$ and O$_2-$N$_2$ systems._x000d_ Reasonable agreement with experimental data is obtained for various near-infrared transitions in both systems._x000d_

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Permalink

http://hdl.handle.net/2142/97194

DOI

https://doi.org/10.15278/isms.2017.WJ12

Copyright and License Information

Copyright 2017 Tijs Karman

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