ExoMol line lists – XXXII. The rovibronic spectrum of MgO

Abstract

AbstractLine lists for magnesium oxide are computed and extensive comparisons are made with existing experimental spectra. The LiTY line lists cover all rovibration transitions within the five lowest lying electronic states ($X\, {}^1\Sigma ^+$, $a\, {}^3\Pi$, $A\, {}^1\Pi$, $B\, {}^1\Sigma ^+$ and $b\, {}^3\Sigma ^{+}$) and five isotopologues: 24Mg16O, 25Mg16O, 26Mg16O, 24Mg17O and 24Mg18O. The calculations use potential energy cures, spin-orbit and electronic angular momentum coupling curves determined by fitting to empirical energy levels; these levels are reproduced to within 0.01 cm−1 in most cases. Computed nuclear-motion wavefunctions are combined with ab initio dipole moment curves to give transition intensities and excited state radiative lifetimes, which are compared with laboratory measurements. The 24Mg16O line list comprises 186 842 (J ≤ 320) rovibronic states and 72 833 173 transitions with angular momenta, J, up to 300 and covering wavenumbers up to 33 000 cm−1 (λ > 0.3 μm). The line lists are suitable for temperatures up to about 5000 K. They are relevant to astrophysical studies of exoplanet atmospheres, cool stars and brown dwarfs, and are made available in electronic form in the CDS and ExoMol databases.