Multiplexed direct-frequency-comb Vernier spectroscopy of carbon dioxide 2 nu1+ nu3ro-vibrational combination band

We investigated a set of nineteen 12C16O2 transitions of the 2?1 + ?3 ro-vibrational band in the spectral region from 5064 to 5126 cm 1 at different pressures, using frequency-comb Vernier spec- troscopy. Our spectrometer enabled the systematic acquisition of molecular absorption profiles with high precision. Spectroscopic parameters, namely, transition frequency, linestrength, and self-pressure broadening coefficient, have been accurately determined by using a global fit procedure. These data are in agreement with theoretical values contained in HITRAN2016 database [I. E. Gordon et al., J. Quant. Spectrosc. Radiat. Transfer 203, 3-69 (2017)] at the same precision level. A moderate improvement of the line intensity determinations, by a factor 1.5 in the best case [P(10) transition at 5091.6 cm 1], should be noticed, projecting direct-comb-Vernier-spectroscopy as an adequate tool for spectral intensity calibration.