The Problem of CO2 Reabsorption in Emission Spectra
J. Heyrovsky Institute of Physical Chemistry
Old Dominion University
University College London
DOI: https://doi.org/10.36956/eps.v2i1.836
Received: 4 April 2023; Published: 17 May 2023
Copyright © 2023 Svatopluk Civiš, Adam Pastorek, Sergei N. Yurchenko. Published by Nan Yang Academy of Sciences Pte. Ltd..
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
Abstract
The authors present a detailed explanation for selective reabsorption by the CO2 ν3-band when passing its optical emission through an atmospheric-pressure air column (60 cm long, 410 ppm CO2) connecting a microwave-discharge cell and the entrance window of a high-resolution Fourier Transform spectrometer. The CO2 band shapes are explained with a two-temperature model of emission and foreground absorption. Selective CO2 atmospheric reabsorption is a common effect in optical emission measurements. It primarily affects the fundamental infrared bands, which comprise the main part of the missing laboratory emission and must be taken into account in (exo)planetary atmospheric models.
Keywords: Reabsorption, Carbon dioxide, FTIR spectroscopy, Vacuum vs air measurement
