Rayleigh Scattering: Collisional Motions in Liquids

Abstract

Measurements of light scattered in the Rayleigh wing were made over the range from 5 to 500 cm⁻¹ in CCl₄, C₆H₁₂, C₅H₁₂, CH₃OH, C₂H₅OH, H₂O, NH₃, and CHCl₃. These data when compared with earlier data on Ar, Xe, and SnBr₄ indicate that in all of these liquids there is present the essentially exponential frequency dependence typical of collision induced effects. A calculation of the spectrum for large frequency shifts based on a binary interaction picture employing a Lennard‐Jones potential and a short range electronic overlap distortion model agrees well with the experimental results in liquid argon. Further, assuming that molecular frame distortion is proportional to the interaction force, a similar calculation yields excellent agreement for the molecular systems. It is concluded that isolated binary interactions are mainly responsible for the spectral density in the wings of the Rayleigh spectrum.