FERMI RESONANCE IN THE ACETYLENIC STRETCHING BAND OF $CF_{3}C \equiv CH$.

Abstract

The abnormal shape of the vapor phase $\nu_{2}$ acetylenic stretching band in the infrared spectrum $trifluoropropyne^{1}$ can be explained by Fermi resonance with $\nu_{4}+\nu_{6}+\nu_{10}$ and the presence of hot bands. In $CF_{3}C\equiv CD$ only the hot bands appear with the $\nu_{2}$ band. Matrix isolation yields a doublet in $CF_{3}C \equiv CH$ and only a singlet in $CF_{3}C \equiv CD$. The observed intensities of the hot bands in $CF_{3}C \equiv CD$ agree with those calculated.