MARVEL analysis of high-resolution rovibrational spectra of the 18O12C18O, 17O12C18O, and 18O13C18O isotopologues of carbon dioxide

Abstract

For three rare isotopologues of carbon dioxide, ¹⁸O¹²C¹⁸O (828, according to a well-established shorthand notation), ¹⁷O¹²C¹⁸O (728), and ¹⁸O¹³C¹⁸O (838), 3923, 4318, and 1058 empirical rovibrational energy levels, respectively, are determined, using the MARVEL (Measured Active Rotational–Vibrational Energy Levels) protocol and code. For the isotopologues 828/728/838, the analysis of their spectroscopic network is based on 11 353(7665)/11 313(7700)/2155(1595) measured(unique) transitions, belonging to 165/113/50 vibrational bands, respectively. The measured transitions collected from the literature span the regions 953–12 570 cm⁻¹ (for 828), 628–8197 cm⁻¹ (for 728), and 600–7918 cm⁻¹ (for 838). The number of critically evaluated and recommended energy levels of this study are 3923, 4318, and 1058 for the 828, 728, and 838 isotopologues of CO₂, respectively. Comparison of the empirical rovibrational energy levels determined in this study with their counterparts in two published databases, CDSD-2019, Ames-2021 and HITRAN shows very good overall agreement.