Knowledge Bank

The Anderson-Tsao-$Curnutte1$ theory of collision-broadened spectral lines, as extended by $Tejwani2$ for octopolar interactions, has been used to compute linewidths for methane broadened by molecular nitrogen and oxygen. Width of vibration-rotation lines in the infrared-active fundamental bands $\nu 2,\nu 3$, and $\nu 4$; the overtone bands $2\nu 3,2\nu 4$, and $3\nu 3$; and the combination bands $\nu 2+\nu 3$ and $\nu 3+\nu 4$ have been calculated for the symmetry species A, E, and F separately, for the range of angular momentum quantum number 0 $\le$ J $\le$ 30. The contribution of the dipole $moment3$ of $CH4$ has been found to be essentially negligible. The temperature dependence of the calculated linewidths has been obtained for the range $200\circ K\le T\le 300\circ K$ . Finally, these results have been used to compute corresponding air-broadened line-widths.