The CW-CRDS spectra of the 16O/18O isotopologues of ozone between 5930 and 6340 cm-1--Part 1: 16O16O18O
Résumé
The first investigation of the very sensitive CW-Cavity Ring Down Spectra (noise equivalent absorption αmin≈1×10-10 cm-1) of 18O enriched ozone isotopologues is reported. The ozone generation from 18O enriched oxygen molecules resulted in six isotopic species. The contributions of the 16O16O18O/16O18O16O and of the 18O18O16O/18O16O18O isotopomers were separated using two partial pressures of 16O2/18O2 mixtures. In the 5930-6340 cm-1 range, the four dominant bands of 16O16O18O were vibrationally assigned as 2ν1+2ν2+3ν3_1, 2ν2+5ν3, 5ν1+ν3 and 2ν1+2ν2+3ν3_2. They correspond to the highest vibration excitations observed so far in an asymmetric CS ozone isotopologue. The rovibrational spectra for 18O enriched CS ozone species show specific features related to the nuclear spin statistics and to simultaneous symmetry allowed Coriolis and anharmonic accidental resonances, which are discussed. Altogether for the four new bands, 2155 rovibrational transitions were assigned up to Jmax=32. Observed line positions were fitted with rms deviations ranging from 0.005 to 0.01 cm-1 using effective Hamiltonian models accounting for dark state perturbations. The derived band centers and rotational constants are in good agreement with new theoretical calculations from the molecular potential function. The corresponding line lists are provided as Supplementary Material.