ELASTIC AND INELASTIC LIGHT-SCATTERING FROM DISTILLING MICRODROPLETS FOR THERMODYNAMIC STUDIES

The evaporation rates of single-component droplets and the related the rmodynamics of binary component droplets consisting of 1-iodododecane and 1-bromotetradecane have been explored using elastic and inelastic (Raman) light-scattering to determine the droplet size and chemical co mposition as diffusion-controlled evaporation proceeded. Single drople ts were levitated electrodynamically in a chamber and exposed to a vap or-free nitrogen gas stream. Elastic scattering data for the single co mponents, obtained at the same temperature, were used to determine the optical parameters and transport process parameters needed to interpr et binary droplet Raman data for mixtures of the halogenated hydrocarb ons. Evaporation rate theory coupled with a UNIFAC thermodynamic model for activity coefficients was shown to agree very well with experimen tal data collected from binary droplets. Results indicate that Raman i ntensity ratios associated with the C-I and C-Br bonds can be used to follow changes in composition quantitatively, but for greater accuracy more detailed analysis of the effects of morpholoqy-dependent resonan ces on the Raman effect is needed.