CRDS measurements of air-broadened lines in the 1.6 µm band of 12CO2: Line shape parameters with their temperature dependence

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

“…In our previous works, 4,32,39 a beat note (BN) signal, between the laser source and the closest tooth of a frequency comb (FC), was used to accurately determine the absolute frequency of the laser source, limited by a laser line width of a few hundred kHz. Here, this signal is used to transfer the coherence of the comb to a fraction of the ECDL output using the feed-forward technique, described in Votava et al 40 and in Gotti et al, 41 providing a driftless and spectrally narrower source directly tunable using a RF synthesizer.…”

“…These missions are increasingly demanding in terms of high quality spectroscopic data for the CO 2 absorption bands in the 1.6 and 2.0 mm regions used for these measurements. In the former spectral region, numerous line profile studies [2][3][4][5][6] as well as highly accurate frequency measurements [7][8][9][10][11][12][13][14] have been reported so far. In particular, transition frequencies with kHz-accuracy were determined both in the Doppler limited regime 8,9,12,13 and in the saturation regime.…”

“…The achieved uncertainty will be valuable for fixing the positions at pressure equal to zero in the multi-spectrum fit procedures used to analyze spectra of CO 2 diluted in air, allowing for the improvement of the other line profile parameters, especially the pressure shift coefficients (see e.g. Mondelain et al 4 ). The obtained frequency values will be also valuable for spectra calibration purposes as for instance for frequency referencing differential absorption LIDAR (LIght Detecting And Ranging) dedicated to CO 2 measurements.…”

Rovibrational Energies of 13C16O2 Determined with Kilohertz Accuracy

“…11−18 However, to improve the accuracy of CO 2 remote sensing and emerging infrared absorption spectroscopy for determining stable carbon isotope ratios, 19 high-precision line parameters of other isotopologues are still required. Line parameters of 13 C 16 O 2 , the second most abundant isotopologue with a terrestrial abundance of 1.1%, are of particular interest. The absorption lines of 13 C 16 O 2 in the same region overlap strongly with the 3001(2,3)e−00001e bands of 12 C 16 O 2 , as shown in Figure 1.…”

“…Line parameters of 13 C 16 O 2 , the second most abundant isotopologue with a terrestrial abundance of 1.1%, are of particular interest. The absorption lines of 13 C 16 O 2 in the same region overlap strongly with the 3001(2,3)e−00001e bands of 12 C 16 O 2 , as shown in Figure 1. The frequencies and intensities of 13 C 16 O 2 lines in this region are currently best determined through theoretical calcula-tions.…”