Global Analysis of the Infrared Spectrum of 13 CH 4 : Lines in the Region 0 to 3200 cm –1

We have carried out new measurements of infrared spectra in a wide frequency range for the spherical top molecules 12 CH 4 , 13 CH 4 and 12 CD 4 at low (80 K) and at room temperature (298 K). Spectra were recorded at very high resolution (0.0027 cm -1 for spectra in the region around 2900 cm -1 , which corresponds to the pentad for 13 CH 4 using the Zurich prototype Bruker 125 spectrometer (ZP 2001) combined with a low temperature cooling cell and a White-type cell. At low temperature, the Doppler full line width at half maximum was reduced by a factor of 1.91 to 0.0045 cm -1 in the pentad region for 13 CH 4 . We report the global analysis of 13 CH 4 -transitions up to 3200 cm -1 and compare to previous work. In the present work line positions are reproduced with an rms deviation of 0.0004 cm -1 . The complex interacting system is analyzed using the effective Hamiltonian approach elaborated in Dijon.