Modelling of the 2ν1-ν1 and ν1 band transitions of 13CH4 using high resolution Raman spectroscopy measurements

• Published in: Journal of quantitative spectroscopy & radiative transfer 2021-08, Vol.270, p.107682, Article 107682
• Main Authors: Chizhmakova, I., Nikitin, A.V., Martínez, R.Z., Paredes-Roibás, D., Bermejo, D., Starikova, E., Tyuterev, Vl.G.
• Format: Article
• Language: English
• Subjects: Effective Hamiltonian; High resolution Raman spectra; Methane; Pentad; Pumped to the excited state; Tetradecad; Vibration-rotation states
• ISSN: 0022-4073; 1879-1352
• DOI: 10.1016/j.jqsrt.2021.107682

•A1 vibrational states of 13CH4 investigated via high resolution Raman spectroscopy.•80 new rovibrational assignments were made for the 2ν1– ν1 band.•line positions were modeled with the RMS deviation of 0.0014 cm−1.•Vibrational levels v1 and 2v1(A1) were found to lie at 2915.4375 and 5784.3436 cm−1. The pump-probe technique for investigating vibrationally excited states via high resolution Raman spectroscopy was applied to 13CH4 methane isotopologue. The dipole transitions between A1 totally symmetric vibrational states are not active in IR spectra but these states can be efficiently studied using selective high resolution Raman spectroscopy. 80 vibration-rotation transitions, most of which belong to the 2ν1– ν1 band have been assigned in the observed Raman spectra reported in this work. Including the Raman transitions in the simultaneous data fit improves the accuracy of the effective Hamiltonian and also rovibrational upper state levels of the ν1, 2ν1 and 2ν3 (A1) bands. A more accurate model of the ν1 vibration-rotation transitions improves the interpretation of the temperature dependence of Raman spectra involving the Pentad and Tetradecad polyads.