$N_{2}$ AND Ar BROADENING OF THE P AND R BRANCHES OF THE $\nu_{3}$ BAND OF METHANE

Abstract

We have recorded ${N_{2}}{-}$ and Ar-broadened spectra of the allowed P-and branch manifolds for $J \leq 10$ in the $\nu_{3}$ band of $CH_{4}$ from the Doppler limit to $\sim 67 kPa at T = 295 K$ using a tunable difference-frequency laser spectrometer. The broadening coefficients and shifts and Dicke narrowing will be compared with prior laser measurements in the Q branch of this $band^{1}$ as well as previous FTIR measurements in the P and R $branches^{2}$. We will also address the question of line mixing between the overlapping tetrahedral components in a given blended J manifold as reported by the NASA Langley $group^{3}$.