HIGH RESOLUTION STIMULATED RAMAN SPECTROSCOPY OF THE $\nu_{1}$ BAND OF $CH_{4}$

Abstract

A Doppler limited CW stimulated Raman spectrum was taken of the $\nu_{1}$ band of methane. This is the first spectrum which clearly shows the Q- branch fine structure. We present line assignments for $J\leq 9$ and spectroscopic constants which differ significantly from previous $^analyses^{1,2}$ In particular, using $Hecht’s^{3}$ notation, we find that the rotational constant $B^{\prime} - B^{\circ}$ is $\Delta B =0.0109\pm 0.0003$ and the tensor splitting constant $t^{\prime}{044}-t^{\circ}{044}$ is $\Delta t_{044}=-(3.7 \pm 0.6)\times 10^{-5}$.