ANALYSIS OF THE $2\nu_{4}$ HARMONIC RAND OF $^{12}CH_{4}$

$^{1}$R. S. McDowell, L. B. Asprey, and R. T. Paine, J. Chem. Phys. 61, 3571 (1974).$^{2}$ (a)W. B. Person and J. H. Newton, J. Chem. Phys. 61, 1040 (1974); (b) J. H. Newton and W. B. Person, J. Chem. Phys. 64, in press (1976); the original paper introducing polar tensors was (c) J. F. Biarge, J. Herranz, and J. Morcillo, Anales Real Soc. Espan., Fis. Quim. (Madrid) A57, 81 (1961). $^{3}$R.T. Paine, R. S. McDowell, L. B. Asprey, and L. H. Jones, J. Chem. Phys. 64, in press (1976).This research was performed under the auspices of USERDA. Willis B. Person was Visiting Staff Member, Summer 1975 and his permanent address is Department of Chemistry, University of Florida, Gainesville. Florida. 32611. John Overend was Visiting Staff Member during 1975 and his permanent address is Department of Chemistry, University of Minnesota, Minneapolis, Minnesota, 55455.Author Institution: University de Dijon; University of TennesseeThe infrared spectrum of the $2_{\nu4}$ vibration rotation band of $^{12}CH_{4}$ has been recorded at $100^\circ K$. The temperature dependence of line intensities made it possible to determine approximate values for the ground-state J values and to assign some lines. We were then able to compute the spectrum using Moret-Bailly’s formalism up to second order of approximation. The spectrum was computed using ten molecular constants for the excited state; the computed spectrum agrees very well with the experimental one. About one hundred transitions were identified; the standard deviation between computed and experimental data is $0.15 cm^{-1}$