Line list of 12CH4 in the 4300–4600 cm−1 region. (September 2020)

• Record Type: Journal Article
• Authors: Nikitin, A.V.; Rodina, A.A.; Thomas, X.; Manceron, L.; Daumont, L.; Rey, M.; Sung, K.; Protasevich, A.E.; Tashkun, S.A.; Chizhmakova, I.S.; Tyuterev, Vl. G.
• Is Part Of: Journal of quantitative spectroscopy & radiative transfer. Volume 253(2020)
• Publication Date: 2020-09
• Subjects: High resolution spectra -- Ch4 -- Methane -- Octad -- Long path ftir, vibration-rotation states -- Intensities -- infrared absorption -- effective Hamiltonian; Spectrum analysis -- Periodicals; Radiation -- Periodicals; Analyse spectrale -- Périodiques; Rayonnement -- Périodiques; Radiation; Spectrum analysis; Periodicals; 543.0858
• DOI: 10.1016/j.jqsrt.2020.107061
• Languages: English
• ISSNs: 0022-4073

Abstract

Highlights: 14, 151 line positions and intensities were retrieved in the 4300- 4600 cm −1 region. More than 7000 new assignments were made in the region. 8605 experimental line positions were modeled to 0.0014 cm −1 . 5402 experimental line intensities at 296 K were modeled to 9.9% rms. Abstract: Four spectra of normal samples of CH4 in the 4300–4600 cm −1 region were recorded by using a Fourier transform spectrometer in Reims, France at long paths (202 m, 602 m, 1604 m, and 1804 m) and different pressures. Additional spectra of 12 CH4 covering the same region were obtained at 80–123 K, and 93 m path length at SOLEIL Synchrotron in Paris for different pressures and were used to measure low-J lines. Line positions and intensities were retrieved by non-linear least-squares curve-fitting procedures and analyzed using effective Hamiltonian and effective dipole transition moment models. A new measured line list contains positions and intensities for 14, 151 absorption features. Quantum assignments were made for more than 10, 304 transitions of 12 CH4, which represent ∼99% of the integrated line intensity observed in this region. Some 1699 hot band transitions for (Dyad – Tetradecad) system were assigned. The resulting list of lines is significantly more accurate than previous empirical compilations. Positions of 8605 cold band transitions for (GS – Octad) system were fitted with an RMS standard deviation of 0.0014 cm −1 . The sum of observed intensities between 4300 and 4600 cm −1 fell within 8% of the predicted value from ab initio variational calculations reported in the TheoReTS database (http://theorets.univ-reims.fr ; http://theorets.tsu.ru ).