ExoMol line lists -- XLVII. Rovibronic molecular line list of the calcium monohydroxide radical (CaOH)

Abstract

Any future detection of the calcium monohydroxide radical (CaOH) in stellar and exoplanetary atmospheres will rely on accurate molecular opacity data. Here, we present the first comprehensive molecular line list of CaOH covering the \A--\X\ rotation-vibration-electronic and \X--\X\ rotation-vibration bands. The newly computed OYT6 line list contains over 24.2 billion transitions between 3.2 million energy levels with rotational excitation up to $J=175.5$. It is applicable to temperatures up to $T=3000$~K and covers the 0\,--\,35\,000~cm${}^{-1}$ range (wavelengths $\lambda >0.29$~$\mu$m) for rotational, rotation-vibration and the \A--\X\ electronic transition. The strong band around 16\,000~cm${}^{-1}$ ($\lambda =0.63$~$\mu$m) is likely to be of interest in future astronomical observations, particularly in hot rocky exoplanets where temperatures can become extremely high. The OYT6 line list has been generated using empirically-refined \X\ and \A\ state potential energy surfaces, high-level \textit{ab initio} transition dipole moment surfaces and a rigorous treatment of both Renner-Teller and spin-orbit coupling effects, which are necessary for correctly modelling the CaOH spectrum. Post-processing of the CaOH line list has been performed so as to tailor it to high-resolution applications, i.e.\ by replacing calculated energy levels with more accurate empirically-derived values (where available), hence improving the accuracy of the predicted line positions in certain regions. The OYT6 line list is available from the ExoMol database at http://www.exomol.com and the CDS astronomical database.

References in corpus (11)

• The 2020 release of the ExoMol database: molecular line lists for exoplanet and other hot atmospheres
• Magneto-Optical Trapping and Sub-Doppler Cooling of a Polyatomic Molecule
• ExoMol molecular line lists X: The spectrum of sodium hydride
• Laboratory spectra of hot molecules: data needs for hot super-Earth exoplanets
• Determination of CaOH and CaOCH${}_3$ vibrational branching ratios for direct laser cooling and trapping
• Accurate prediction and measurement of vibronic branching ratios for laser cooling linear polyatomic molecules
• A high-resolution line list for AlO
• ExoMol line lists -- XLV. Rovibronic molecular line lists of calcium monohydride (CaH) and magnesium monohydride (MgH)
• ExoMol line lists -- XLI. High-temperature molecular line lists for the alkali metal hydroxides KOH and NaOH
• MARVEL analysis of the measured high-resolution rovibronic spectra of the calcium monohydroxide radical (CaOH)
• Theoretical rovibronic spectroscopy of the calcium monohydroxide radical (CaOH)

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