THE RAMAN SPECTRUM OF GASEOUS $CH_{2}D$

Abstract

The rotation-vibration Raman spectrum of gaseous $CH_{3}D$ has been photographed with a reciprocal linear dispersion of 3 to $5 cm^{-1}mm$ and a practical resolving power of $0.4 cm^{-1}$. The spectrograms were obtained with 1.6 l of the gas at atmospheric pressure and exposure times of 8 to 32 hours. In the $2800 to 3250 cm^{1}$ region 325 lines were measured; these lines belong chiefly to the doubly degenerate $\nu_{4}$ band on which the totally symmetric $\nu_{1}$ and $2\nu_{4}$ bands are superimposed. Since the selection rules for the $\nu_{4}$ band are $\bigtriangleup K =\pm 1, \pm 2$, and $\bigtriangleup J =0 \pm 1, \pm 2$, the rotational structure is rather complicated. The use of an electronic computer in analysing such a band will be described. It is interesting to note that transitions corresponding to $\bigtriangleup K =O$ appear, although they are forbidden by the selection rules. The influence of the Fermi resonance on the rotational structure of $\nu_{1}$ and $2\nu_{3}$ will be discussed.