Electric-quadrupole and magnetic-dipole contributions to the ν2+ν3 band of carbon dioxide near 3.3 µm

The update of the line positions and intensities in the line list of carbon dioxide for the HITRAN2020 spectroscopic database

“…The calculated line intensities were consistent with an intensity cut-off 10 -30 cm/molecule at 296K. The calculated line intensities agree well with the values measured independently by Optical-Feedback-Cavity Enhanced Absorption Spectroscopy (OFCEAS) in Fleurbaey et al [58] for five Rbranch lines of this band (R26-R32 and R36). An overview of the 01111-00001 magnetic dipole band of the main CO2 isotopologue with band center 3004.012 cm -1 is displayed in Fig.…”

“…We should also mention that in their OFCEAS study of the v2+v3 band, Fleurbaey et al [58] reported together with the detection of the magnetic dipole lines, the measurement of weaker electric quadrupole of the same v2+v3 band. This detection was made possible by accurate ab initio predictions of the E2 line intensities 12 C 16 O2 in the 0-10000 cm -1 range [60].…”

“…16. The 01111-00001 magnetic dipole band of the main CO2 isotopologue [56,58]. The band center of this band is 3004.012 cm -1 .…”

Electric quadrupole transitions in carbon dioxide

“…A very recent laboratory study, dedicated to measurements of the weak spectral features in the S-branch of ν 2 + ν 3 band of CO 2 by OFCEAS [25], has confirmed the strong M1 features originally observed in martian CO 2 . The measurements have also revealed a number of new features that can be assigned, by comparison with theoretical line list, to the S12, S14, and S16 E2 lines, shown in Fig.…”

“…In this contribution, we report the first complete and accurate E2 line list for carbon dioxide 12 C 16 O 2 , which was validated in the 3.3 µm transparency window by recent laboratory measurements using Optical-Feedback-Cavity Enhanced Absorption Spectroscopy (OFCEAS) [25]. Based on our predictions and laboratory measurements, we report a detection of the E2 lines in the martian atmospheric spectra recorded by the Ex-oMars Trace Gas Orbiter Atmospheric Chemistry Suite (ACS) instrument [26].…”