ExoMol line lists – LX. Molecular line list for the ammonia isotopologue 15NH3

Abstract

Abstract A theoretical line list for 15NH3 CoYuTe-15 is presented based on the empirical potential energy and ab initio dipole moments surfaces developed and used for the production of the ExoMol line list CoYuTe for 14NH3. The ro-vibrational energy levels and wavefunctions are computed using the variational program TROVE. The line list ranges up to 10 000 cm−1 (λ ≥ 1 μm) and contains 929 795 249 transitions between 1 269 961 states with J ≤ 30. The line list should be applicable for temperatures up to ∼1000 K. To improve the accuracy of the line positions, a set of experimentally-derived energy levels of 15NH3 is produced using the Marvel procedure. To this end, 37 experimental sources of the line positions of 15NH3 available in the literature are collected, combined and systematised to produce a self-consistent spectroscopic network of 21 095 15NH3 transitions covering 40 vibrational bands ranging up to 6818 cm−1 and resulting in 2777 energy term values. These Marvel energies are then used to replace the theoretical values in the CoYuTe-15 line list and also complemented by pseudo-Marvel energies obtained by an isotopologue extrapolation using the previously reported Marvel energies of the 14NH3 parent isotopologue of ammonia. A list of 53 856 high resolution transitions between Marvel states and theoretical intensities is provided in the HITRAN format. Comparison with the recent experimental spectra of 15NH3 illustrate the potential of the line list for detections and as an efficient assistant in spectroscopic assignments. The line list is available from www.exomol.com.