Analysis of the interacting Octad system of (CH4)-C-12

The octad system of methane (CH4)-C-12 has been analyzed with a fourth-orde r (459 parameters) Hamiltonian for energy levels and a third-order (28 para meters) dipole moment expansion for infrared intensities. Nearly 8000 assig ned positions and 2500 measured line intensities (obtained with the Fourier transform spectrometer located at Kitt Peak National Observatory/National Solar Observatory) have been considered in the modeling. Infrared (Octad-Gr ound State) and hot bands (Octad-Dyad) data have been used, While the model does not reproduce the measurements at their inherent experimental precisi ons, it has been sufficient to interpret and substantially assign this spec tral region of methane for the first time in over 30 years of investigation , (C) 2001 Academic Press.