12CO2 transition frequencies with kHz-accuracy by saturation spectroscopy in the 1.99–2.09 μm region

0573391 - ÚFCH JH 2024 RIV GB eng J - Journal Article
Fleurbaey, H. - Čermák, P. - Campargue, A. - Kassi, S. - Romanini, D. - Votava, Ondřej - Mondelain, D.
12CO2 transition frequencies with kHz-accuracy by saturation spectroscopy in the 1.99–2.09 μm region.
Physical Chemistry Chemical Physics. Roč. 25, č. 24 (2023), s. 16319-16330. ISSN 1463-9076. E-ISSN 1463-9084
Institutional support: RVO:61388955
Keywords : spectroscopy * optical materials * frequency standards * fight measurement
OECD category: Physical chemistry
Impact factor: 3.3, year: 2022
Method of publishing: Open access

Saturation spectroscopy has been used to determine the absolute frequencies of 107 ro-vibrational transitions of the two strongest 12CO2 bands of the 2 μm region. The considered 20012-00001 and 20013-00001 bands are of importance for the CO2 monitoring in our atmosphere. Lamb dips were measured using a cavity ring-down spectrometer linked to an optical frequency comb referenced to a GPS-disciplined Rb oscillator or to an ultra-stable optical frequency. The comb-coherence transfer (CCT) technique was applied to obtain a RF tunable narrow-line comb-disciplined laser source using an external cavity diode laser and a simple electro-optic modulator. This setup allows obtaining transition frequency measurements with kHz-level accuracy. The resulting accurate values of the energy levels of the 20012 and 20013 vibrational states are reproduced with a (1σ)-rms of about 1 kHz using the standard polynomial model. The two upper vibrational states appear thus to be highly isolated except for a local perturbation of the 20012 state leading to an energy shift of 15 kHz at J = 43. A recommended list of 145 transition frequencies with kHz accuracy is obtained providing secondary frequency standards across the 1.99–2.09 μm range. The reported frequencies will be valuable to constrain the zero-pressure frequencies of the considered transitions in 12CO2 retrieval from atmospheric spectra.

Permanent Link: https://hdl.handle.net/11104/0343851