Isotopic substitution shifts in methane and vibrational band assignment in the 5560–6200 cm −1 region

• Published in: Journal of quantitative spectroscopy & radiative transfer Vol. 110; no. 12; pp. 964 - 973
• Main Authors: Nikitin, Andrei V., Mikhailenko, Semen, Morino, Isamu, Yokota, Tatsuya, Kumazawa, Ryoichi, Watanabe, Takeshi
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-08-2009
• Subjects: CH 4 molecule; Isotopic shift; Methane absorption; CH 4 molecule; Methane absorption; Isotopic shift
• ISSN: 0022-4073; 1879-1352
• DOI: 10.1016/j.jqsrt.2009.02.016

The absorption spectra of the
12CH
4 and
13CH
4 molecules have been recorded and assigned in the 5560–6200
cm
−1 region. The effects of isotopic substitution for
12C by
13C on the methane vibrational energy levels have been calculated from an
ab initio potential energy surface and compared with experiment. Comparison of the results obtained for two isotopic species allows us to confirm the vibrational assignment for the strongest bands of
12CH
4 in this region. Good agreement of
ab initio calculations with observed energy levels has been demonstrated. A list of the assigned
13CH
4 lines valuable in atmospheric applications is reported.