Knowledge Bank

The infrared absorption spectra of $CF4$ and $CCl4$ have been observed in both the pure form and in rare gas matrices at low temperatures. The region studied corresponded to the $\nu 3,2\nu 4$ and $\nu 3,\nu 1+\nu 4$ Fermi doublets of $CF4$ and $CCl4$ respectively. The interaction of the vibrations in Fermi resonance in these molecules changes considerably from that found in the gaseous phase. The spectral features observed will be discussed and related to recent theories.