First assignment of the 5nu4 and nu2+4nu4 band systems of 12CH4 in the 6287-6550 cm-1 region.

Andrei Nikitin (1, 2) , Xavier Thomas (2) , L. Regalia (2) , L. Daumont (2) , Pierre von der Heyden (2) , Vladimir G. Tyuterev (2) , Le Wang (3) , Samir Kassi (3) , Alain Campargue (3)

1 LTS - Laboratory of Theoretical Spectroscopy [Tomsk]
2 GSMA - Groupe de spectrométrie moléculaire et atmosphérique
3 LSP - Laboratoire de Spectrométrie Physique

This paper reports the first assignment of rovibrational transitions of the 54 and 2+44 band systems of 12CH4 in the 6287-6550 cm-1 region which is usually referred to as part of the 1.6 m methane transparency window. The analysis was based on two line lists previously obtained in Grenoble by Cavity Ring Down Spectroscopy at T= 297 K and 79 K completed by three long path Fourier Transform Spectra recorded in Reims (L=1603 m, P= 1-34 mbar). In order to determine the dipole transition moment parameters and quantify the intensity borrowing due to the resonance interactions, we had to include in the fit of the effective Hamiltonian model some lines of the stronger 1+34 and 2+44 bands. For this purpose, intensities of 179 additional lines were retrieved from FTS spectra above 6550 cm-1 though the analysis of these higher bands is not complete. About 1955 experimental line positions and 1462 line intensities were fitted with RMS standard deviations of 0.003 cm-1 and 13.4%, respectively. A line list of 8027 calculated and observed transitions which are considered as dominant was constructed for 12CH4 in the 6287-6550 cm-1 region. This is the first high-resolution analysis and modeling of 5-quanta band systems of 12CH4.

Domaines: Physique Atomique [physics.atom-ph]; Optique [physics.optics]

Andrei Nikitin, Xavier Thomas, L. Regalia, L. Daumont, Pierre von der Heyden, et al.. First assignment of the 5nu4 and nu2+4nu4 band systems of 12CH4 in the 6287-6550 cm-1 region.. Journal of Quantitative Spectroscopy and Radiative Transfer, 2011, 112, pp.28-40. ⟨10.1016/j.jqsrt.2010.08.006⟩. ⟨hal-00563224⟩