Decoupling of Light Scattering and Absorption Contributions to Extinction in Pickering Emulsions

Abstract

Direct transmittance spectra of Dodecane based Pickering emulsions are inverted to obtain the spectral behavior of their intrinsic scattering and absorption coefficients per unit length, µ_sca and µ_abs respectively. The spectral range includes ultraviolet, visible, and near infrared wavelengths. Dynamic light scattering has been used to characterize the bimodal lognormal size distribution of the ensemble of particles or micelles. Lorentz-Mie theory is applied to show how the morphology and composition of the particles influence the scattering and absorption cross sections. A spectral projected gradient method is applied to carry out the inversion of transmittance spectra. Three light scattering and absorbing particles in water are considered: those consisting of submicron-sized Dodecane micelles, Dodecane particles capped with self-assembled nano-sized anatase (TiO2) particles, and similar ones anatase capped Dodecane micelles with dissolved Nile Red dye.