Abstract

The far infrared absorption spectra of pure liquid CS₂ and CCl₄ and of their mixtures at three different mole fractions have been obtained at room temperature. The integrated absorption, the effective dipole moments and the dipole correlation functions have been calculated. The results indicate that these quantities of the mixtures cannot be calculated as a sum of additive contributions of the pure components. The applicability of two different models, an isolated binary interaction model and a concentration fluctuation model, is discussed. The changes of the spectra and of the induced dipole autocorrelation functions with composition are interpreted in terms of a time-dependent cancellation of molecular dipoles by local fluctuations of density, concentration and molecular orientation.