Analysis of the CRDS spectrum of 18O3 between 6950 and 7125 cm−1

Abstract The absorption spectrum of the 18 O 3 isotopologue of ozone was recorded by CW-Cavity Ring Down Spectroscopy in the 6950–7125 cm −1 region. The typical noise equivalent absorption of the recordings is α min ≈1×10 −10  cm −1 . The spectrum is dominated by three very weak bands: 3ν 1 +5ν 3 near 7009 cm −1 and the ν 2 +7ν 3 and 4ν 2 +5ν 3 interacting bands near 7100 cm −1 . In total 260, 206 and 133 transitions were assigned for the 3ν 1 +5ν 3 , ν 2 +7ν 3 and 4ν 2 +5ν 3 bands, respectively. The line positions of the 3ν 1 +5ν 3 band were modelled using an effective Hamiltonian (EH) model involving two dark states – (6 0 1) and (2 5 2) – in interaction with the (3 0 5) bright state. The EH model developed for the ν 2 +7ν 3 and 4ν 2 +5ν 3 bands involves only the (0 1 7) and (0 4 5) interacting bright states. Line positions could be reproduced with rms deviations on the order of 0.01 cm −1 and the dipole transition moment parameters were determined for the three observed bands. The obtained set of parameters and the experimentally determined energy levels were used to generate a list of 984 transitions of the three bands which is provided as Supplementary Material.