High sensitivity cw-cavity ringdown and Fourier transform absorption spectroscopies of 13CO 2

Abstract

The absorption spectrum of 13CO 2 has been recorded by cw-cavity ringdown spectroscopy with a new set up based on fibered DFB lasers. By using a series of 31 DFB lasers, the spectrum of carbon dioxide could be recorded in the 6130–6750 cm −1 region with a typical sensitivity of 5 × 10 −10 cm −1. The spectrum has also been recorded between 4400 and 8500 cm −1 with a Fourier transform spectrometer associated with a multi-pass cell (maximum path length of 105 m). The new observations obtained both by FTS and CRDS represent a significant extension of the available data. For instance, more than 4000 line positions were measured and assigned in the CRDS spectrum while only 232 line positions are listed in the HITRAN database. Altogether, the band by band analysis has led to the determination of the rovibrational parameters of 65, 7, and 24 bands for the 13C 16O 2, 16O 13C 17O, and 16O 13C 18O isotopomers, respectively. As some observed line positions show significant deviations from the predictions of the effective Hamiltonian model, the new observed line positions were gathered with the data available in the literature to refine the set of effective Hamiltonian parameters of the 13C 16O 2 isotopic species. The refined set of 96 effective Hamiltonian parameters reproduces more than 14 650 line positions of 13C 16O 2 with an RMS=0.002 cm −1. A detailed comparison with the line positions retrieved from Venus spectra and the line list provided by HITRAN is also presented and discussed.