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ExoMol line lists -- LXIII: ExoMol line lists for 12 isotopologues of CO$_2$

Sergei N. Yurchenko, Marco G. Barnfield, Charles A. Bowesman, Ryan P. Brady, Elizabeth R. Guest, Kyriaki Kefala, Qing-He Ni, Armando N. Perri, Oleksiy A. Smola, Andrei Solokov, Chenyi Tao, Jonathan Tennyson

Abstract

Extensive rovibrational line lists are constructed for 12 isotopologues of carbon dioxide: $^{12}$C$^{16}$O$_2$, $^{13}$C$^{16}$O$_2$, $^{12}$C$^{17}$O$_2$, $^{13}$C$^{17}$O$_2$, $^{12}$C$^{18}$O$_2$, $^{13}$C$^{18}$O$_2$, $^{16}$O$^{12}$C$^{17}$O, $^{16}$O$^{12}$C$^{18}$O, $^{16}$O$^{13}$C$^{17}$O, $^{16}$O$^{13}$C$^{18}$O, $^{17}$O$^{12}$C$^{18}$O, and $^{17}$O$^{13}$C$^{18}$O. The variational program TROVE was employed together with an exact kinetic energy operator, accurate empirical potential energy surface (Ames-2) and the ab initio dipole moment surface Ames-2021-40K. Empirical energy levels from the most recent MARVEL analyses, as well as from the HITRAN and CDSD databases, are used to replace calculated values where available. The line lists are further supplemented by assigning AFGL quantum numbers using machine-learning based estimators. The resulting data were employed to generate opacities with four radiative transfer codes, TauREx, ARCiS, NEMESIS, and petitRADTRANS, both for individual isotopologues and for CO$_2$ at terrestrial isotopic natural abundance. All line lists and associated data are available at www.exomol.com.

ExoMol line lists -- LXIII: ExoMol line lists for 12 isotopologues of CO$_2$

Abstract

Extensive rovibrational line lists are constructed for 12 isotopologues of carbon dioxide: CO, CO, CO, CO, CO, CO, OCO, OCO, OCO, OCO, OCO, and OCO. The variational program TROVE was employed together with an exact kinetic energy operator, accurate empirical potential energy surface (Ames-2) and the ab initio dipole moment surface Ames-2021-40K. Empirical energy levels from the most recent MARVEL analyses, as well as from the HITRAN and CDSD databases, are used to replace calculated values where available. The line lists are further supplemented by assigning AFGL quantum numbers using machine-learning based estimators. The resulting data were employed to generate opacities with four radiative transfer codes, TauREx, ARCiS, NEMESIS, and petitRADTRANS, both for individual isotopologues and for CO at terrestrial isotopic natural abundance. All line lists and associated data are available at www.exomol.com.

Paper Structure

This paper contains 18 sections, 7 equations, 10 figures, 4 tables.

Table of Contents

  1. Introduction
  2. Rovibrational states of CO$_2$ isotopologues: quantum numbers and selection rules
  3. Rotational quantum number and parity
  4. Symmetry group classification
  5. Selection rules
  6. Line list production
  7. Potential Energy Surface
  8. Dipole Moment Surface
  9. Variational nuclear-motion calculations
  10. Empirical corrections of $J=0$ energies
  11. MARVELisation procedure
  12. Rovibrational line lists for CO$_2$ isotopologues
  13. Using machine learning to reconstruct spectroscopic quantum numbers
  14. Partition functions
  15. Opacities
  16. ...and 3 more sections

Figures (10)

  • Figure 1: Obs.-Calc. residuals for $^{12}$C$^{16}$O$_2$ and $^{13}$C$^{18}$O$_2$ using two Ames PESs, Ames-2 17HuScFr.CO2, shown with red circles, and Ames-X01d 23HuFrTa.CO2, shown with blue crosses.
  • Figure 2: 'Obs.-calc'. residuals for different isotopologues using two Ames PESs, Ames-2 17HuScFr.CO2 and Ames-X01d 23HuFrTa.CO2, before (red circles) and after (blue crosses) the band centre corrections 09YuBaYa.NH3. The green crosses in the display 628 show the divergence of the band-centre-corrected energies with $J$ increases (see text).
  • Figure 3: Coverage of the assigned states with the AFGL quantum numbers per isotopologue comparing to the corresponding empirical assignments: Marvel, HITRAN or CDSD-2024-PI.
  • Figure 4: Partition functions for $^{12}$C$^{16}$O$_2$: comparison of Dozen with TIPS 2024 of HITRAN2024 jt981 and Ames AI-3000K.
  • Figure 5: Spectra of CO$_2$ isotopologues at $T=1000$ K (Gaussian profile, HWHM = 1 cm$^{-1}$). Intensities are not scaled to isotopic abundances.
  • ...and 5 more figures