Knowledge Bank

Measurements performed at temperatures between $80\circ K$ and $295\circ K$ are presented for collision-broadened rotational lines in the $\nu 3$ fundamental and $2\nu 3$ band of $CH4$. Half-widths of methane lines have been measured in self-broadening and in broadening by hydrogen, helium, nitrogen and air. Our measurements at temperatures below $100\circ K$ reveal, for the first time, the nature of the far wings of methane lines. Similar measurements have also been made on the far wings of lines in the fundamental band of CO.