Fig. 4

Overview of all assigned lines. Total view of the transitions that were rotationally assigned in this work. The regions containing assigned lines are printed colour-coded, while the containing raw spectra are printed in grey. The colours denote the isotopologues and the vibronic states that were accessed by transitions from the vibronic ground state \({\mathrm{X}}0_{\mathrm{g}}^ +\) (v = 0) with the corresponding rotational quantum number J″ as denoted on the ordinate. Starting from the bright transitions that were unambiguously assigned by double-resonant selection of J″, blocks of excitation scans into the dark regimes could be also assigned by numbering consecutively