Comparative study of infrared and Raman spectra of CCl 4 in vapour and condensed phases: Effect of LO–TO splitting resulting from hetero-isotopic TD–TD interactions

Abstract

Salient features of an in-depth comparative study of infrared and Raman spectra of CCl 4 in vapour, liquid and condensed phases are presented. Wavenumbers of ν 4, ν 1 + ν 4, ν 3 and 2ν 3 modes of CCl 4 vapour in infrared and Raman spectra are found to be in good agreement. Analysis of the vibrational spectra of liquid CCl 4 together with the spectroscopic observations on solid CCl 4 at low temperatures reveal TD–TD interaction amongst various CCl 4 isotopes in condensed states. The concept of LO–TO splitting of dipole active ν 3 and ν 1 + ν 4 Fermi doublet have been invoked to explain several features of the vibrational spectra of liquid CCl 4. There is significant strengthening of Fermi resonance interaction between ν 3 and ν 1 + ν 4 modes of CCl 4 in condensed phases relative to that in vapour phase. The Fermi resonance interaction parameter W has been found to be independent of molecular environment.