Rotational spectroscopy of imidazole: Accurate spectroscopic information for three vibrationally excited states and the heavy-atom isotopologues up to 295 GHz

We report our analysis of the pure rotational spectra low-lying vibrationally excited states and heavy-atom rare isotopologues imidazole. To facilitate searches for imidazole in interstellar medium, we previously described spectrum main isotopologue across 2–295 GHz range, extend this here. Structure optimisation anharmonic frequency calculations were performed to aid spectral analysis. Three assigned room-temperature spectra, with energies up approximately 670 cm?1 above vibronic ground state. The vibrational could act as temperature probes warmer star-forming regions. 13C 15N assigned, which allowed structure gas phase be determined. Structural comparisons are drawn between related heterocyclic molecules hydantoin imidazolidine. An experimental gas-phase former is also determined work. potential detection help deduce formation pathways towards other nitrogen-containing cyclic compounds space.