Analysis of measured high-resolution doublet rovibronic spectra and related line lists of CH and OH.

Detailed understanding of the energy-level structure of the quantum states as well as of the rovibronic spectra of the ethylidyne (CH) and the hydroxyl (OH) radicals is mandatory for a multitude of modelling efforts within multiple chemical, combustion, astrophysical, and atmospheric environments. Accurate empirical rovibronic energy levels, with associated uncertainties, are reported for the low-lying doublet electronic states of CH and OH, using the Measured Active Rotational-Vibrational Energy Levels (MARVEL) algorithm. For CH, a total of 1521 empirical energy levels are determined in the primary spectroscopic network (SN) of the radical, corresponding to the following seven electronic states: X Π, A Δ, B Σ, C Σ, D Π, E Σ, and F Σ. The energy levels are derived from 6348 experimentally measured and validated transitions, collected from 29 sources. For OH, the lowest four doublet electronic states, X Π, A Σ, B Σ, and C Σ, are considered, and a careful analysis and validation of 15 938 rovibronic transitions, collected from 45 sources, results in 1624 empirical rovibronic energy levels. The large set of spectroscopic data presented should facilitate the refinement of line lists for the CH and OH radicals. For both molecules hyperfine-resolved experimental transitions have also been considered, forming SNs independent from the primary SNs.