COLLISION-INDUCED EFFECTS IN THE FINE-STRUCTURE RESOLVED SPECTRAOF ATMOSPHERIC OXYGEN FROM FIRST PRINCIPLES: THE EFFECT OF O₂-N₂ SCATTERING

Gancewski, Maciej

Permalink

https://hdl.handle.net/2142/122480 Copy

Description

Title

COLLISION-INDUCED EFFECTS IN THE FINE-STRUCTURE RESOLVED SPECTRAOF ATMOSPHERIC OXYGEN FROM FIRST PRINCIPLES: THE EFFECT OF O₂-N₂ SCATTERING

Author(s)

Gancewski, Maciej

Contributor(s)

• Wcislo, Piotr
• Dawes, Richard
• Quintas Sánchez, Ernesto
• Jóźwiak, Hubert

Issue Date

2023-06-21

Keyword(s)

Atmospheric science

Abstract

The properties of our planet’s atmosphere are derived from models which are mostly based on remote-sensing data. A detailed knowledge of spectra of various chemical compounds making up the terrestrial atmosphere is therefore crucial for understanding the various ongoing kinetic and dynamic processes. As these compounds are not isolated, intermolecular interactions involving most abundant atmospheric constituents – N₂ (∼ 78%) and O₂ (∼ 21%) – may affect the shapes of the spectra under consideration. In this context, oxygen spectra are of particular interest. O₂ is a prominent example of a diatomic molecule with a ³Σ ground-electronic term, and fine-structure resolved transitions involving this term have a wide range of applicability – from monitoring the plant vegetation status on the Earth’s surface, to the quantification of the pollutant concentration in the atmosphere [J. Quant. Spectrosc. Radiat. Transf. 186, 118 (2017)]. Here, we consider the effect of O₂-N₂ collisions on the shape of the oxygen spectral lines from the theoretical point of view. Utilizing the exact close-coupling approach, we calculate the relevant scattering amplitudes based on the ab initio intermolecular potential energy surfaces (PESs). We account for the non-zero spin of the X³Σ− term of O₂ by performing a unitary transformation on the spin-free S-matrix, which allows us to compute the line shape parameters for the fine-structure resolved transitions in O₂ immersed in the bath of N₂. Having successfully tested our methodology against the experimental data in our previous study of the 118 GHz fine-structure transition in O₂(X³Σ−) [J. Chem. Phys. 155, 124307 (2021)], we apply it to the problem of N₂-perturbed lines in the oxygen A-band (i.e., electronic transition b¹Σ⁺ ← X³Σ−). This problem is more challenging as it requires the use of two PESs in the scattering calculations. The PESs used in this study were constructed automatically using the AUTOSURF 262 (2018)].

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

Text

Language

eng

Handle URL

https://hdl.handle.net/2142/122480

Owning Collections