Critical evaluation of measured rotational–vibrational transitions of four sulphur isotopologues of S16O2. (March 2018) - Tóbiás, Roland
Highlights: A critical evaluation and validation of the complete set of previously published experimental rotational–vibrational line positions is reported for four stable sulphur isotopologues of the semi-rigid S 16 O2 molecule. The conventional and a J -dependent rotational Hamiltonian methods are used to assess vibrational parent and asymmetric-top rotation quantum number labels. The extensive list of lines and levels of the isotopologues studied are deposited in the distributed information system ReSpecTh (http://respecth.hu/ ). Abstract: A critical evaluation and validation of the complete set of previously published experimental rotational–vibrational line positions is reported for the four stable sulphur isotopologues of the semirigid SO2 molecule – i.e., 32 S 16 O2, 33 S 16 O2, 34 S 16 O2, and 36 S 16 O2 . The experimentally measured, assigned, and labeled transitions are collated from 43 sources. The 32 S 16 O2, 33 S 16 O2, 34 S 16 O2, and 36 S 16 O2 datasets contain 40, 269, 15, 628, 31, 080, and 31 lines, respectively. Of the datasets collated, only the extremely limited 36 S 16 O2 dataset is not subjected to a detailed analysis. As part of a detailed analysis of the experimental spectroscopic networks corresponding to the ground electronic states of the 32 S 16 O2, 33 S 16 O2, and 34 S 16 O2 isotopologues, the MARVEL (Measured Active Rotational–Vibrational Energy Levels) procedure is used to determine the rovibrational energy levels. The rovibrational levels and their vibrational parent and asymmetric-top quantum numbers are compared to ones obtained from accurate variational nuclear-motion computations as well as to results of carefully designed effective Hamiltonian models. The rovibrational energy levels of the three isotopologues having the same labels are also compared against each other to ensure self-consistency. This careful, multifaceted analysis gives rise to 15, 130, 5852, and 10, 893 validated rovibrational energy levels, with a typical accuracy of a few 0.0001 cm − 1, for 32 S 16 O2, 33 S 16 O2, and 34 S 16 O2, respectively. The extensive list of validated experimental lines and empirical (MARVEL) energy levels of the S 16 O2 isotopologues studied are deposited in the Supplementary Material of this article, as well as in the distributed information system ReSpecTh (http://respecth.hu ).