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Journal Articles Journal of Quantitative Spectroscopy and Radiative Transfer Year : 2022

Simultaneous collision-induced transitions in H2O+CO2 gas mixtures

Abstract

A collision induced absorption (CIA) band has been measured near 60 0 0 cm −1 in a spectrum of humidified CO 2 recorded by cavity ring down spectroscopy (CRDS) at low pressure (< 1 atm). This absorption adds a contribution to the H 2 O + CO 2 continuum mostly originating from far wings of the CO 2 and H 2 O resonance lines broadened by collisions with H 2 O and with CO 2 , respectively. The observed CIA corresponds to a simultaneous excitation of 12 CO 2 and H 2 O colliding molecules in the ν 3 antisymmetric and ν 1 symmetric stretching mode, respectively. CRDS spectra recorded near 5940 cm −1 with a highly enriched 13 CO 2 sample provide a confirmation of the assignment since the measured CIA isotopic spectral shift (of about −68 cm −1) coincides with that between the ν 3 bands of 12 CO 2 and 13 CO 2. The integrated binary coefficient of the two CIA is evaluated and found to be on the order of 2.3 × 10 −3 cm −2 amagat −2. Classical molecular dynamics simulations (CMDS) of the considered CIA are also presented, based on the dominant dipole induction mechanism associated with the vibrational matrix elements of the dipole of CO 2 (ν 3) and isotropic polarizability of H 2 O (ν 1). The results of the calculations are found in good agreement with the observations, thus further validating the attribution of the observed CIA structure to the above mentioned double transitions.
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Dates and versions

hal-03854982 , version 1 (21-11-2022)

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H Fleurbaey, Didier Mondelain, W Fakhardji, J M Hartmann, A Campargue. Simultaneous collision-induced transitions in H2O+CO2 gas mixtures. Journal of Quantitative Spectroscopy and Radiative Transfer, 2022, 285, ⟨10.1016/j.jqsrt.2022.108162⟩. ⟨hal-03854982⟩
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