Comparative study of infrared and Raman spectra of CCl4 in vapour and condensed phases: Effect of LO–TO splitting resulting from hetero-isotopic TD–TD interactions

Salient features of an in-depth comparative study of infrared and Raman spectra of CCl4 in vapour, liquid and condensed phases are presented. Wavenumbers of ν4, ν1 + ν4, ν3 and 2ν3 modes of CCl4 vapour in infrared and Raman spectra are found to be in good agreement. Analysis of the vibrational spectra of liquid CCl4 together with the spectroscopic observations on solid CCl4 at low temperatures reveal TD–TD interaction amongst various CCl4 isotopes in condensed states. The concept of LO–TO splitting of dipole active ν3 and ν1 + ν4 Fermi doublet have been invoked to explain several features of the vibrational spectra of liquid CCl4. There is significant strengthening of Fermi resonance interaction between ν3 and ν1 + ν4 modes of CCl4 in condensed phases relative to that in vapour phase. The Fermi resonance interaction parameter W has been found to be independent of molecular environment.