New assignments and a rare peculiarity in the high sensitivity CRDS spectrum of acetylene near 8000 cm−1

Recommended acetylene 12C2H2 line list in 13.6 µm spectral region: New measurements and global modeling

“…Interesting case of band crossing is also presented in Ref. [20]. In the present work, several newly observed bands demonstrate such smooth rotational dependence of R 2 and are well predicted by previous calculations [1,4].…”

The 2020 edition of the GEISA spectroscopic database

“…The EDB17 covers the range of the ΔP = 9-14 series excluding the 6341-7000 cm -1 interval roughly corresponding to the ΔP = 10 series. The EDB17 was constructed by gathering results of three studies by Fourier transform spectroscopy [103][104][105] and three studies by cavity ring down spectroscopy (CRDS) [106][107][108]. In the regions of low absorption, the sensitivity of the CRDS technique enabled the detection of weak lines with intensities on the order of 10 -29 cm/molecule.…”

“…For all 12 C2H2 and 12 C 13 CH2 isotopologues, the vibrational assignment has been changed to V1 V2 V3 V4 V5 ℓ4 ℓ5 from V1 V2 V3 V4 V5 ℓ, where ℓ is the sum of ℓ4 and ℓ5. Indeed, the ℓ4 and ℓ5 quantum numbers are necessary to assign the various bands that include strong resonance interactions between ro-vibrational states [100][101][102][103][104][105][106][107][108] used to update the GEISA-2020 database. Based on the new vibrational assignment and the symmetry E/F of the rotational levels, the symmetries +/-have been generated for all transitions of both isotopologues, and symmetry u/g have been generated only for symmetric 12 C2H2 isotopologue.…”

High sensitivity absorption spectroscopy of acetylene near 1.2 µm

“…Our analysis used spectra recorded by Fourier-transform spectroscopy (FTS) in the region of the strong bands and by cavity ring down spectroscopy (CRDS) in the weak absorption intervals. In 2017, by gathering the results of three FTS [9][10][11] and three CRDS [12][13][14] studies, we constructed a first version of our spectroscopic database (DB2017, hereafter) covering the 5850-9415 cm -1 region (excluding the 6341-7000 cm -1 interval) [15]. As a rule, the DB2017 list relies on a band-by-band modeling: the acetylene line positions were calculated using empirical spectroscopic parameters of the lower and upper energy vibrational levels and intensities were computed using the vibrational transition dipole moment squared and Herman-Wallis coefficients derived, for each band, from a fit of measured intensities.…”