The Infrared Spectrum of Methyl Chloride

Abstract

Certain new infrared absorption bands of C${\mathrm{H}}_3$Cl were mapped in the region from 0.7μ to 7.0μ. In each case the bands show the structure predicted by the theory of the symmetry properties of molecules having three equal atoms. It is also predicted that every third line in the ⊥ bands shall be enhanced. This was observed in the present investigation as well as previously by Bennett and Meyer. Several new intervals between the lines in the ⊥ bands were observed which may be of value with regard to a theoretical interpretation of this anomalous spacing. Two absorption regions, observed here, appear to give evidence of an interaction between the levels ${\nu }_1$ and $2{\nu }_4$ thought to exist in some of the methyl compounds. These bands are ${\nu }_2+({\nu }_1, 2{\nu }_4)$ at 5900 ${\mathrm{cm}}^{-1\mathrm{}}$ and ${\nu }_3+({\nu }_1, 2{\nu }_4)$ at 4200 ${\mathrm{cm}}^{-1\mathrm{}}$. A few lines of ${\nu }_3$ in the $P$ branch near the center were resolved. The $Q$ branch proved to be much more pronounced than Bennett and Meyer's work shows.