Line positions and intensities for the ν2/ν4 bands of 5 isotopologues of germane near 11.5 μm

Abstract Germane is a tetrahedral molecule found in trace abundance in giant gas planets like Jupiter and Saturn. We have recently provided a database of calculated lines of the stretching fundamental bands in the 2100  cm − 1  region that is of high interest for planetology ( https://vamdc.icb.cnrs.fr/PHP/GeH4.php ). It is now necessary to study many rovibrational levels, including the lowest ones, in order to access the hot bands and thus to improve the model of the spectral region of interest for Jupiter, especially in the framework of the ongoing Juno mission. We present here a complete analysis and modeling of line positions and intensities in the ν 2 / ν 4 bending dyad region near 900  cm − 1  for all five germane isotopologues in natural abundance. Thanks to the high symmetry of the molecule, we use the tensorial formalism and group theory methods developed in the Dijon group, that allows us to provide a set of effective Hamiltonian and dipole parameters. The present study also leads to a refined value of the Ge–H equilibrium bond length of 1.51714(25) A. Finally, new calculated germane lines were derived and injected in the GeCaSDa database.