Full spectroscopic model and trihybrid experimental-perturbative-variational line list for CN

Accurate line lists are important for the description of the spectroscopic nature of small molecules. While a line list for CN (an important molecule for chemistry and astrophysics) exists, no underlying energy spectroscopic model has been published, which is required to consider the sensitivity of transitions to a variation of the proton-to-electron mass ratio. Here we have developed a Duo energy spectroscopic model as well as a novel hybrid style line list for CN and its isotopologues, combining energy levels that are derived experimentally (Marvel), using the traditional/perturbative approach (Mollist), and the variational approach (from a Duo spectroscopic model using standard ExoMol methodology). The final Trihybrid ExoMol-style line list for (CN)-C-12-N-14 consists of 28004 energy levels (6864 experimental, 1574 perturbative, the rest variational) and 2285103 transitions up to 60000 cm(-1) between the three lowest electronic states (X (2)Sigma(+), A (2)Pi, and B (2)Sigma(+)). The spectroscopic model created is used to evaluate CN as a molecular probe to constrain the variation of the proton-to-electron mass ratio; no overly promising sensitive transitions for extragalactic study were identified.

Automated summary

The researchers developed a Duo energy spectroscopic model and a hybrid style line list for CN and its isotopologues, providing a more accurate description. The final line list consists of 28004 energy levels and 2285103 transitions, used to evaluate CN as a molecular probe for the proton-to-electron mass ratio variation. No overly promising sensitive transitions for extragalactic study were identified.