THE INFRARED SPECTRA OF CERTAIN METHYL HALIDES

Abstract

The infrared spectra of $CH_{3}C1$, $CH_{3}Br$, $CD_{3}Br C^{12}H_{3}1, C^{13}H_{3}I$, and $C^{12}D_{3}I$ have been re-examined between 3000 and $500 cm^{-1}$ using high resolving power. Considerable improvement has been obtained over nearly all previous observations on these molecules. In $CH_{3}I$ it has been possible to resolve clearly a regular fine structure between the Q branches of the perpendicular frequency at $880 cm^{-1}$. This has been possible because the P and R lines arising from various Q branches happen to coincide or nearly coincide. Improved values have been obtained for a large number of the molecular constants. These new values show some interesting features which will be discussed.