| Autor: |
Fleurbaey, H., Čermák, P., Campargue, A., Kassi, S., Romanini, D., Votava, O., Mondelain, D. |
| Zdroj: |
Physical Chemistry Chemical Physics (PCCP); 6/28/2023, Vol. 25 Issue 24, p16319-16330, 12p |
| Abstrakt: |
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. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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