High sensitivity of the anomalies in the rotational and ro-vibrational bands of carbon monoxide to small changes in the molecular potential and dipole moment

Abstract

We compare the intensities of purely rotational and ro-vibrational transitions within the ground electronic state of CO calculated with two dipole moment functions (DMFs) of Li et al. (2015) and four potential energy functions (PEFs), a semi-empirical PEF of Meshkov et al. (doi: https://doi.org//10.5281/zenodo.1198744) and three empirical ones due to Coxon and Hajigeorgiou (2004, 2016, 2017). All these PEFs reproduce the experimental line positions with similar normalized standard deviations (NSDs), and the energy mismatch between the vibrational levels with v⩽5 does not exceed 0.0002 cm−1 among all PEFs. Despite these similarities, we find that the rotational anomalies in the 0-0, 1-1, 2-2, 3-3, 4-4, and 5-0 bands shown in Figs. 3 and 4 of Medvedev et al. (2017) change their intensities by a factor of 2 to 250 among the above PEFs at a given DMF. Both the positions and intensities of the anomalies change between two DMFs at a given PEF.