Absorption spectrum of the (CF4) dimer in liquid argon solution

Abstract

The concentration dependence of the shape of absorption bands in the spectrum of CF4 in liquid argon is studied in the concentration range (0.01–17)×10−3 molar fractions at 93 K. In all spectral regions related to ν3, the shape of the spectral function is determined, along with the Fermi resonance 〈νi,ν3+1,ν4|≈〈νi,ν3,ν 4+2|, by the resonance dipole-dipole interaction. In the spectral region of the Fermi doublet ν 1+ν3≈ ν1+2ν4, the spectrum of the contact (CF4)2 dimer is identified. Agreement between this spectrum and the calculated spectrum is achieved by simultaneously taking intramolecular and intermolecular resonances into account. The distance R C-C in the dimer is 4.85(15) A. The calculations of the spectra of (12CF4)2 and (13CF4−12CF4) dimers with this value of R C-C in the region ν 3≈2ν4 agree with the experiment.