Experimental determination of singly scattered light close to the critical point in a polystyrene–cyclohexane mixture

Abstract

In turbid media the presence of multiple scattering constitutes a major complication for the analysis of the intensity and of the intensity correlation functions of the scattered light. The 3D-cross-correlation technique provides an effective means to determine the single scattering intensity and to suppress the influence of multiple scattering to the time dependence of correlation functions. The technique is applied to study the temperature dependence of the critical fluctuations of a solution of polystyrene (M_w=1.11×10⁵ g mol^-1) in cyclohexane. We show that the single scattering intensity determined for a scattering angle of ϑ=90° can be described by the Ornstein–Zernike function over the entire temperature range of 313.15–293.49 K. Good agreement between experiment and Monte Carlo simulations of the scattering processes is found for the ratio of singly scattered light to the total scattering intensity.